Best PvP healers in Cataclysm (WoW)?

That depends on your take of pvp healing, they're all good, restoration druids in full resilience could take quite a bit of abuse given their amount of HOTs, same case with holy paladins given their ability fo wear plate and wield shields and can throw out a quick heal to their partner if needed when they build up a bit of holy power, restoration shamans have an arsenal of useful totems and can heal very efficiently, discipline priests are good at keeping a single target alive with their bubbles and can do a bit of damage/healing with penance. Your choice of what you want to play as is personal preference since all healing classes can get the job done.