From my playing experience Paladin and Shaman can provide the strongest heals in high dampening (not sure why) and are both less vulnerable to dispels compared to other healers. Paladins are less viable to be trained compared to Shamans because of high armor and shields.
Also have to say that playing Paladin + Warlock I have yet to lose a game against a Hunter comp and as Hunter comps really plague 2v2 currently this gives you a lot of games to win. Hardest opponents are Rogue teams on the other hand, especially with a Resto Druid.
what game are u playing?