Old darius > new one Old veigar > new one Old fizz > new one old irelia > new one old kassadin >>>>>>>>>>>>>>>>>>>>>>>> new one old akali > new one original ryze > new ones old leblanc (with silence) > new one old nidalee > new one old yi > new one old kha > new one old soraka > new one ahri in 5.2 > new one
but there are few that are better now, like 
You mean the old Kassadin that literally had a ~90% ban rate because he was just THAT overbearing?
To fit the game.
uhhhhhhhhhhhhhh
original ryze was definitely not better than the machine gun perma-shield, aoe nuke+dps, perma-speed ryze that got replaced with the current one
old irelia was a 1v1/1v2 split pusher who couldn't teamfight, new irelia needed to be constantly nerfed and things picked out of her kit in order to get a semblance of balance
"old veigar" couldn't get 2 stacks with 1 q. i wouldn't really call changing a single ability a "rework"
old nidalee was only good because of its misleading Q hitbox and absurd ap ratio
old akali was just easier
only real change i can remember from kassadin was the removal of silence on his q (still interrupts channels), the ADDING of the magic shield on it, reduction of his r range, and reduction of damage.. wouldn't call that a rework either
yi "rework" was mostly just a VU, replacing the AP ratio on his Q with an AD ratio and allowing his q to crit
#actual reworks are usually far stronger than the previous iteration and need to be toned down significantly after re-release
Many of those weren't stronger or the old ones you are referring to haven't even been reworked. LB is a good example of that. The current lb is the same as the old LB but just without the silence and removing the silence is not a rework.
I disagree on couple of them. For exaple, old darius could stack on a single person and even if he achieved 5 stacks he didnt get more damage (passive) or with 1 auto to next champion to instaly apply 5 stacks of bleeding. Also the current darius ult deals true damage.
Which new irelia version are you talking about? The pre W change or post W ( they removed the magic damage migation it had) and R ( it had disarm). The new one has arguably 1 of the the stongest lv1 passives in the game. Now the new one isnt suitable to fight against top laners because she lost her W true damage and she has hard time against the previous champions she countered. But Irelia with her rework completly change identity from a tanky diver to similar to yasuo/fiora identity. Their identiteis function completly different and we cant really compare dissimilar things.
Old soraka vs new soraka. New soraka has longer Q and she can poke from safety and her E is an AOE silence with a root her W now cost health. The old one has 0.5-0.9 sec Q spam with short range that reduce MR and her E could either silence 1 or give mana to allies. The old one had the potential to outDPS the new one but she needed to be melee range to do so and thats dangerous unless she went tank but then she would heal for much. In my opinion as a player who played soraka from season 4 and have mastery 7 ( the 2nd mastery 7 i got) i think new soraka is stronger than the old one because the new one has skillshot (new Q and E vs the point-and-click Q and E) so she has more counterplay and that allowed Riot to buff her and make her stronger.
I dont know about ahri situation so I am not suitable to tell my opinion.
For the rest of the group i agree that the old versions were way stronger and lack any meanifull counterplay and that made them unbalanced and broken and OP.
PS You havent search enough and miss a 2 picks. Old jax and old xin zhao were absolute nightmares that could 1v5 alone and towerdive under enemy fountain. Jax now its getting back to the lvs of power in early League but stilll he cant 1vs5 pentakill under enemy fountain and xin is so nerfed that is kinda pointless to pick him instead of lee sin ( maybe in gold or lower that players arent THAT skillfull and lee sin is tad to much to play him correcly then xin zhao or Vi are the best altenative).
Which old morde?
