Ice- Very High single target damage, two holds (one sucky one: Bitter Freese Ray)
Radiation- A heal (does NOT make you a healer), amazing debuffs, a v good buff, and a PBAoE toggle hold.
Grav/NRG Dominator rawks 
If you want to be buffer/debuffer the corruptor is the way to go. There are two primaries I would consider viable choices in your situation: ice/ for -slow and -recharge (and really good single target damage) and sonic/ for -res (stackable and combined with /kinetics a nightmare for opponents with high res). Rad/ and dark/ debuff too, but I think they are not that good overall although rad/ has some nice synergy with /kinetics.
As a secondary I also have two suggestions, although it is really down to what you want for concept and/or playstyle: /kinetic for superior buffing/debuffing of speed and damage (with the disadvantage of being forced to play like a lunatic) and /rad for the ability to debuff anything to nothingness (but the need to explain anchors to team members). Again, there are other sets for buffing/debuffing, but I do not think they are on par with the above-mentioned two.
My favourite corruptors are an ice/rad and a sonic/kin. Both can, if played well, easily turn the tide of a difficult AV battle to the team´s favour.
If it has eyes, you can blind it, if it has blood, you can make it bleed, if it has a mouth, you can make it scream.
If no one else will mention /cold I will. Its without a doubt my favourite corruptor to team with, I have no idea what it's like to play but it makes me feel super powered having one on the team. The debuffs are nice, the buffs are handy and Heat Loss is the best end recovery I've ever been on the end of.
"Well, they found my diary today.
They were appropriately appalled
at the discovery of the eight victims
They're now putting it all together.
Women wrapped in silk
with one leg missing
Eight legs, one body, silk,
spider, brilliant!"
Good to see ya crossing over mate 
I have one suggestion make a brute and do some fighting for once ya Sissy
Or make a kinetic corr so ya can buff my brutes 
not allowed matron soz, now get bk to teh goodies!!! :>
Poke tyl =O oh no he didnt!
Thanks for all the helpful advice , i finally plumped for an Ice/cold corruptor, it's only lev 12 atm but i'm really enjoying it so far ! [img]/uk/images/graemlins/smile.gif[/img]
So, after spending a fair bit of time heroing, I've decided to take the plunge and make a villain . My dilemma tho is what to make, most of my heroes are trollers or defenders ,and i like the support role within a team , so i'll be looking to make a corruptor or dominator but there my knowledge ends !
I'm looking more for something that can buff the team or debuff the nasties, as i won't be soloing it much , tho the ability to be annoying to heroes in the pvp zones would be a plus
I realise it's there's probably many types that would do the job ,but any suggestions are very welcome .
Ta