Quite honestly I cant think of one. Karma, Trundle, Nidalee, Rengar, Xerath, Skarner, Sona, now Cass and Soraka and all the reworks I didnt mention. All had some serious hate going towards them
My message to you guys; I know you hate any changes to your favourite champion, but reworks arent just for you, they are for the whole community and balance.
I havn't been playing league long enough to see many reworks, but the amount of crap riot gets for balancing is unbelievable.
With the exception of numbers for the nidalee GU( AD scalings too high, AP nid too weak), the reworks i've seen have done a good job with the champion.
I loved the Heimerdinger and Sivir reworks though I played Sivir less.
Note how they preserved the core of each champions gameplay (the short ranged high damage high risk carry and the strategic turret placing push Mage) while also maintaining their lore and base visuals (IE Heimerdinger is not now the Freljordle who invented mighty enchanted Ice Guardians to defeat Lissandra.) Sivir they kept her lore and just updated her with more champion interaction and used her to advance a plot-the very first time they'd done that since JoJ closer down-if I were a Sivir main id be honored by that. Both are incredibly balanced right now.
Reworks that were by general consensus good: Sivir Heimer Twitch VU Annie VU Sejuani Victor, Maokai
Reworks that were balanced and are now good: Yi, Skarner, Xerath, Gragas
Beef with the visuals/lore: Garen Karthus Trundle
Beef with the gameplay: Kassadin Rengar Nidalee Sona
Beef with everything: Karma
I'm undecided on cass and Soraka. Initially I like Sorakas direction and cass, id have to play her to see how much I like the free farm and spam sustain from TF, and I'll have to judge her visual on the new map
You're not even addressing why players dislike the Cassiopeia rework, which is completely in line with why previous reworks have also been liked or disliked.
Sonas Rework: Her theme is a musician both inspiring and magically powerful to the point holding her own in battle. Most people liked this rework, but as its really new, still agree it could use some work.
Heimerdingers rework: Heimers theme is that of an eccentric weapon spawning engineer, his rework pushed that to the max, also a generally liked rework, which had some tweaks after the fact.
Karmas rework: Absolutely despised by pretty much everyone that played karma, her theme was that a diplomatic proponent of balance. Her old kit honestly didn't bring this to bear particularly well either, but the rework is even less so. Her theme was outright destroyed. She helps no one, the diplomatic support flavor is gone, nothing balance-y about her. And worst of all, her ultimate was her true niche, it allowed you to cycle between interesting offensive, defensive, and supportive effects; the new ultimate is just a power boost, use it when its up to deal more damage, or an unnoticeable amount of sustain in one case.
Sivir's rework: Also not particularly well received, but not absolutely hated. Her niche was her boomerang blade, that pushed her theme as the bandit queen, someone who would find some way of getting to you and getting what she wanted, through both strongarming as well as trickery and guile. Her theme wasn't destroyed, but it was severely weakened with changes to her boomerang blade attacks.
In short, people are rejecting Cassiopeia's rework for the same reason they have accepted or rejected others, it isn't supporting what people enjoy about the character, the theme and playstyle players pick her up for. People play Cass because she is a high damage poison mage, people hate playing against her because too much burst combined with a CC causes that poison to be nigh inescapable. But instead of pushing her poison mage theme further, as they should, they are watering it down in the favor of utilty, and the worst decision of all, making a late game carry, which are thematically unengaging and mechanically unhealthy for the play environment.
I think it's only natural for people to react this way; they have their main for a reason, they like them as they are; changes (aside from buffs) are typically going to be poorly received by the people who play them. I hated the Gragas rework when I first saw it; still pretty mixed about it tbh. On the other hand, I was pretty excited about the Nidalee rework, since I thought she'd still be a strong mid laner; boy was I wrong about that, and I'm pretty mixed about it now too, since I mostly played AP Nidalee.
Objectively I understand that these changes were necessary, and honestly healthier for the game, but it is sort annoying when your champion pool dries up since old champs you played are no longer as viable in a particular role, and you don't like playing them in the other roles.
I used to main Evelynn, and I really loved her rework. Made her viable in ranked play, with the new stealth mechanic making her play pattern much more interesting and requiring more skill, while also making her feel more like an assassin by needing to carefully stalk her prey from outside their detection range.
But then the S4 vision rework happened, which made her strong, and she got repeatedly nerfed until her AP assassin role has been replaced by a tanky-AD-bruiser - which I hate. In this case, the rework was great, but the aftermath of the rework ruined the champion for me.
Karma - I didn't main her, but I did play her a before her rework. While I do miss some parts of her old kit (around people to tag them with Spirit Bond), I liked the new Karma more, and mained her for a while after the rework.
Katarina - Another rework which I liked. It nicely moved power away from her annoying and kind of uncounterable Q harass, while adding more nuance into her play patterns (by needing to use W , and needing to proc the Q mark for full damage.) In this case, she was initially undertuned (when her passive didn't fully reset her E at lower ranks), but she was quickly buffed into a good state.
Skarner - I didn't play him much before the rework, but picked him up a little while afterwards. I thought he was quite good and fun to play, and he slowly started to replace Eve as my main jungler (for the reasons mentioned above). The final mini-rework that gave him the stun passive made him even better, though I don't think he was that far off even before it.
Xerath - I liked it. I agreed with what Riot said when they reworked him - his old kit was strong, but it was somehow unsatisfying and very binary - either you had your ult up and you were a god, or you had it down and you were very weak.
Rengar - don't play him. Perhaps a little hypocritical for someone who used to play pre-rework Eve, but I hated the way his kit rework made him able to just appear from stealth and instantly kill anyone when he's ahead, with very little counterplay - not helped by the S4 vision system.
Nidalee - I always loved her character, but I hated what she had become before her rework - randomly throwing spears for almost no cost and with a very low cooldown until she hit one and won a fight. The new Nidalee feels far more healthy for the game, while still fun to play. The only thing I don't like about it is that it buffed her AD bruiser role too much (and even changed over all her recommended items to AD ones.) I feel that the new AP Nidalee is balanced and healthy, but the AD bruiser one is little overtuned, and I'm not quite happy with that direction.
All this said, I'm very worried about the Soraka rework. I loved playing Soraka in both solo lane and as a support, and felt both were in a good place. I never understood why there was so much hatred for AP Soaraka - she had decent sustain, but not that great since she didn't max W, she had good waveclear, but other champions have better, often for cheaper. She had some free poke / damage, but it wasn't that impressive damage-wise. She was also increadibly easy to gank or burst down with hard CC. Riot said that they thought supports should be allowed to play mid so long as they bring something different to the team than a normal mage - e.g. they get fed and can support harder with stronger utility, rather than more damage - which is what AP Soraka did. But when people realised she was actually viable there, Riot nerfed both AP Soraka and support Soraka into the worst champion in the game, even worse than Olaf.
Now, the new kit has no damage. She's a heal-bot whose only non-heal spells have long cooldowns. Her only source of damage is a skillshot on a long cooldown, and the damage has been taken off her E, which now has a massive cooldown. I fear she'll only be able to sit next to people to heal them, and barely able to interact with the enemies in her lane much at all. Mid, top, or jungle Soraka will be completely destroyed since she has no damage and not much ability to heal herself.
Sivir's rework was pretty to be honest
My utter and complete distaste for the upcoming Soraka rework comes from one fact :
Forcefully forbidding her to build defense elements by making it either actively detrimental for health, or not scaling as well as on any other champion when it comes to resistance - only recieving a portion of the defensive stats for an unknown return.
Her current kit, regardless of the numbers, made it optimal to go tanky** without Riot game designer suspecting it at first**. This design looks like both a vengeance and railroading Soraka into the path Riot sees for her and nothing else.
Trundle rework complain is about visual in general, Xerath rework complain is not that strong, Sona is not very strong and some people actually like it.
For Rengar the complain is more about earlier patch in game nerf, during rework the complain is minor.
Gragas rework complain is minor too.
Karma rework receive a lot flame, I mean shit load.
Heimerdinger rework might be the most successful one, and I hardly hear complain about it.
People just hate Knidalee period, and after rework a lot people still hate Nidalee.
Not all rework was hate equally, and current Soraka kite receive hate almost equal to Karma rework.
I was slightly worried on xearth but I liked it, I felt his W was worthless, (Old) And his new one works better.
I kinda like the Cass one, as one of the seemingly few Cass players. Just wish it wasn't like "you're all about damage, so only one of your skills does any damage"
There will always be people who will be angry at change.
If a champion gets fully reworked, there's the thought of, "Why don't you just make a whole new champion with that kit if you're going to change my main that much!" and/or "the months I spent getting good at this champion are down the drain!".
My message to you guys; I know you hate any changes to your favourite champion, but reworks arent just for you, they are for the whole community and balance.
Or, if you see it from another point of view, some of them are there to turn niche playstyle that some enjoy into global playstyle that we already have tons of.
Switch it to a more common playstyle is like saying "you play and enjoy the game since a long time? Guess what, you play it wrong, come with all the other player"
I mean, If you don't like one playstyle, well, just don't play it. (no need to get rid of it unless it's toxic and op has hell, but it wouldn't be niche if it is^^)
Of the champs I was familiar with and liked to play, I can't think of any that's been a genuine homerun. The closest was Sona but that was more of a sidegrade that was unasked for by sona players and people are saying it didn't work out well for her.
For example rito was supposed to have reworked eve after killing her old kit but she's been constantly nerfed to the point she almost can't jungle or lane. I don't even play olaf but it's called getting olafed for a reason.
Reworks. How you can love and hate them.
Evelynn - rework was amazing, and as someone who played pre-rework evelynn a ton I can say that I loved it. Yeah you could be seen in stealth at close range, so lesss cheese, but everything else in her kit made up for it, she dealt plenty of damage, had counterplay (against organized teams, she messed up soloqueue much as shaco can). Eve was a rework I was happy about. The constant nerfs make it so I don't play her much anymore, but I did, agian, enjoy the initial rework (hate spikes pre rework hit 2 targets, 1 for 100% and another for 50% and did little damage if I recall).
Heimerdinger - I didn't, nor do I main heimerdinger, but a friend of mine was very happy with the changes, his only irritation was the lack of slow, but pressing R and getting a ton of rockets, a giant turret, or the underrated bouncing stun, the lack of slow on towers was easily made up.
Sivir - Again I played Sivir a lot pre-rework (typically in a svir/raka bully lane) but alone I loved playing her too. Even more so after the rework as W and E were greatly improved. Initially the Q was better too but they have balanced it out since (which is fine). I still enjoy playing sivir, even after some nerfs to her damage. (The E buff was a godsend - no mana cost).
Sejuanni - Again not a champion I mained, but another friend of mine said she was amazing (and she was) post rework before they nerfed her numbers and CC not long after.
Gragas - Mixed feels on this. Gragas needed the change ultimately, and while we will all miss 1 shotting people, I understood that his playstyle and kit didn't match his lore and was unhealthy (You can't be an assassin, tank, mobile AoE Zoning Mage).
Master Yi - Many people hated the lack of AP scaling loss on Q. AP yi players hated the change, however the few amount of AD yi players loved it quite unanimously from my understanding. (His lore/kit scream AD as well).
Karma - ...
Kassadin - Well, we new it was coming, and those who could relished in the joy of his lack of counterplay did, those who couldn't banned him. The change was needed and we all knew it, but nobody really wanted to admit to wanted to give up 1v5 crazy mobility assassinations.
LeBlanc - The initial kit rework (changing mainly the ult) was loved, the removal of silence made life a bit sad for her though and currently her kit is once again lacking.
Nidalee - I like and disliked this rework. AP nid spears and sustain was a problem, she could kill people easily with very little built and with little counterplay. I like the implementation of her cougar and human form, at least the idea, but the AD scaling on Q (an execcution amplified by landing human form spells) made her a split push champ with little counterplay. She's still frustrating to play against, and when I play her I hate going AD for the sake of one spells scaling.
Sona - Not really a buff or nerf IMO, kinda of a side-slide of power. It hurt her sustained power but gave her instant power. Her solo lane potential was killed, but she can still make some pretty clutch saves with her W. I think her problem isn't her kit, she's just outclassed by much stronger and slightly unhealthy champs such as Nami, who brings Sona's Q and W in the form of her W, a reliable low CD stun, and a more reliable and larger AoE Stun/Slow ult.
Rengar - Not a rengar player, don't really know any rengar players.
Taric - People LOVED the taric rework, but he got nerfed directly after and became unviable to play against, again, the stronger supports of today (Thresh, Braum, Ali).
Viktor - As far as I can tell most Viktor players are excited for what has been spoiled (as an occasional player of him I am) since he gets all his augments, his W could be a little more reliable, and his item will give a ton of AP and be a good item to have in slot from what I understand.
Will add more below --v--
I mained or played heavily 
(prior to reworks) and was extremely pleased with reworks, while initial one was really lacking, though with the stun passive now I like it a lot more, though I am still iffy towards the rework.
Frankly, what bothers me the most is that Riot ignores the theme of champions at times during reworks.
Karma, for instance, will never actually be karmic again:
Before, hurting Karma made her hurt you, Her abilities were offensive or defensive based on choice:
Her Q did damage but could also heal Using her W on an enemy meant it was easier for your allies to benefit, but harder (impossible) to do damage Her E was a shield but could also do damage
Everything with the old Karma was a give/take relationship, now she just spams Q.
And they ruined her Sakura skin, she isn't even a Geisha anymore since she has no fans.
Might as well rename the champion.
I loved the Sivir ones, the Trundle one ( even if i miss the old Trundle lore, now he has his own place on the story... plus, it' s still the old troll :D ), THE OLAF ONE ( I HATED TO PICK MY AXES ON MY FEET. WHY I HAD TO THROW AXES ON MA FEET?), the Master Yi one ( yay, no more AP ) aaand i guess personally speaking it' s enough, even if i liked also most of all the others like Skarner and Heimer.
