Honestly i dont think theres that much difference in dungeons, and healers should be able to keep all 3 tanks up fairly well while doing dps even with aggresive tanks with proper use of cooldowns.

But if we talking amount of heals in tank stance i still have to throw warrior into the mix, they have a selfheal as strong as the pld heal, Thrill of Battle which increases your hp by 20% and heals for as much as it increased it, as well as inner beast that's both a defensive buff and selfheal and steel cyclone an aoe enmity move that selfheals