In no particular order, the champions from the last 3-4 months
Galio: Area of effect taunt, which enhances other AOEs + good damage. This makes galio into a beast in an AOE team.
Vlad: Area of effect damage increase + a good chunk of health at the end of it. This makes Vlad into a beast into an AOE team.
Xin Zhao: Point blank area of effect
Kog'Maw: Long range, small impact AOE
Miss Fortune: Massive cone area of effect
In fact, the only champ I can think of which isn't in that is Urgot, who is widely considered to be UP.
I play Mumu, Morg and whoever with the best of them, I like me some AOE... But get a LITTLE original on some new ultis.and expand playstyles just a little bit.