Tank class with worst reputation.

[Enosh]

DKs for being the most derp, that is people consider the players to be idiots
monks for being the "hardest to heal", in this case people don't really blame the players but more blizzard for making monks spiky etc (even through it's often a player error and not a class design issue)

[Sanssanity]

Well played dks are awesome. Unfortunately...most are not well played.

I don't see a lot of druids.

Warriors/paladins are usually adequate - although not usually spectacular.

Monks - such a mixed bag. I find playing one fun - tanking just feels different. But I main a healer... most of the ones I see outside of guild runs are not fun.