Dunno about all tanks, but prot paladins have some survivability. First they can heal, of course. But with Word of Glory, they do so with instants, and without mana. Just need three holy power thingies, but with their fairly low cooldown on their abilities, it comes back very often.
Biggest problem I've had so far was against Ret paladins, that can heal just as well, but have a better damage/survivability ratio. I just have more HP, that they chew through eventually. Could be solely because I'm full Talasite for now, could fare better with a bit more offense.
I have a prot warrior as well. Fun, but not survivable at all. The only thing you'll kill are levelers, and even then, hunter or mage, well...
Edit : I have a DK and druid as well. Havent played the DK as blood yet(frost currently), but their Runic power generation seems too low for them to be good. Plus, death strike was nerfed to hell. Havent been able to play my Bear Druid, but faced some, they seem okay-ish.