First of all it's a matter of what lane(role) you want to play.
My suggestion is save your ip. I know it hard to bypass the excitement of a new champion but hear me on this one!
Your playstyle will change alot.
I have over 110 champion out of which i play fewer than half of them. I wish i hadn't bought some of them.
Play more, learn your style, which lane/role you lile the most and then you can buy 3-4 champions that fit this role better.
If you want a quick opinion on the champs you mentioned.
Ziggs is alot of fun however a little unreliable as he is all skillshots that if you don't land you do no dmg. He is ok but i wouldn't recommend buying him yet.
He is a mid laner, se may play him top but mid lane it is.
Yorick is really strong in top lane, i guess you could play him mid but that would be a troll pick. He is a good lane bully vrs meele champs but i wouldn't recommend him aswell.
Vladimir is also a top laner and mid laner, he is equally good in bith, he is an amaxing champion that requires experience to play. When i first bought him i thought he was terrible and hated him, as i got better in the game i absolutely loved him. He is really strong against some champions but really weak against others. I suggest getting more experience in the game before you buy vlad.
Victor is also a mid laner, i guess you could play him top, but it would be so great. He is also skill shot depended his e may take some practice to master, his ult can be awkward to use, i like victor but i wouldn't recommend him to a newbie.
Skarner is my least played champ in this list, he is jungler and some people play him top. His ult is awesome but i would jist stay away from skarner, the other champions in the list seem way better choices.
Shyvana is awesome. She is a top lane/jungle tank. You could buold her to do dmg but its pointless as her abilities are not that high dmg output. She is tho an absolute beast and after you build a couple items she is so hard to kill. She works fine with the current meta and she looks awesome, i mean she is a dragon! I would consider buying her but hold your horses my top pick isn't here yet. Shyvana if you like to do alot of dmg isn't that great tho.
Nocturne is a jungler and you can't really play him elsewhere, he is a nice champion if his ult had lower cd i would play him more, as the only way to get a good gank is by ulting. There are far better junglers so i wouldn't pick him.
Imma put malzahar and oriana together as they are bith pure midlaners. Oriana can play support too. They have decent dmg, oriana has more burst but malzahars dots are nkt to be underestimaded. His ult is sick. I love them both. Most ppl would say oriana is better as she was nice utility butalzahar is awesome. You can beat champs like yasuo at ease with malz.
Last but not least irrelia. Definitely the best on this this lost i would go with irrelia over anyone in this lost. She is a top laner only but she is awesome. After you get a trinity force you are prtty much a huge threat dmg wise with decent survivability.
I would definitely give her a try.
Now imma mention a couple more champs in this 4800 range that are awesome and you should consider.
Ahri is amazing
Caitlin really good adc
Brand is also good burst mid lane mage
Fizz really strong, but i wouldn't buy him in this meta
Cassiopeia is a little hard to master but has insane dmg!
Ezreal is a good mid laner and adc he can be great if he gets alittle ahead.
Graves the absolute adc beast atm. Prolly the easiest and best adc in the game.
Jarvan is a beast much better jungler that nocturne and he is a game changer champion.
Kog maw if you like a hyper carry.
Kennen for an unkillable top laner that does awesome dmg.
Maokai for top lane and i play him sup too. He is awesome brings stun and alot of utility for the team.
Riven is a beast in top lane. Master her mechanics and melt people down. No mana no energy just spam the shit out of your abilities.
Vayne the tabk killer
Rumble is a good top laner but more advanced so stay away from him for now
Sejuani if you want an unkilable jungler with amazing ganks and so many ch utility
And of course wukong, my favorite monkey, really easy to play with alot of carry potential his ult is awesome so is his jukes.
My pick out of all 4800 champions would be
Graves for adc
Ahri for mid lane
Jarvan for jungle
Leona for support
And shyvana or irrelia for top
I hope this helps!!!