Druids are the best spell cleave healers, they can heal most comps with some success. They are not a potential kill target, which is very important. They are not susceptible to training either. They can play long games, and short games via tree form spam and hotw dps if needed.
Priests are good with hunter rushdown comps, due to initial shielding and fear. They usually can't do 2min+ games because of mana and bad healing outside shields.
Shamans can play melee/caster and double caster but they get trained and killed(even though I attribute some of that to the shamans not adapting to the new healing system, not healing much, doing other stuff, jumping around because a 350k could fix anything or facerolling with es+ riptide + healing stream at any time previous patches)
Paladins, they do good with melee cleaves, they are still killed by wizards. They do good also with hunter comps, not as good as disc priest.
Monk, I don't know what they are doing, I haven't seen anything amazing from them so far.
That said, if every healer played their best comp for the ladder, in my opinion the list would look like this:
This would be very different if we made a list with survivability / mana / healing output / cc / cc avoidance, overall better healing class(and not how they fit in with broken class comps)
Edited by Djandawg, 28 May 2013 - 04:02 PM.