There is a reason that fire is so common, though. And it is actually pretty fun. I mostly play AOE focused ranged characters - usually variants of farming builds as corruptor / blaster.
By by far my favorite toon has been fire/storm corruptor. The damage is obscene at times and the AOE damage is enough that most single target attacks ( and a good amount of AOE’s) are at the least enhanced by scourge, and often overkill the targets.
In the past few days I’ve been working with a sonic/storm variant, and I’ve got to say it’s been very pleasantly surprising. If you get enough resistance debuffs layered and then toss out ionic, for instance, the AOE damage becomes AOE delete. Literally zapped a +4 boss on a fire map from about 60% health to dead, from just ionic after applying debuffs. I think sonic damage may actually be very competitive with fire in some scenarios. So that might be interesting for you. Just play with the sound OFF. lol
I would avoid water if I were you. I’ve done several aoe focused water builds and, while water offers a very complete set, it gets out paced very quickly. And the fun factor goes away when you’re just watching mobs bounce, without any real damage