
Me personally I've seen a ton of mages, a good number of warlocks, and then a healthy number of Rogues/Warriors. Following that is probably Paladins, and then for hunters and druids I don't even know if they exist since I haven't seen them.
I'm only in the sub-20s though, and I believe that this changes later on (many warriors give up due to difficulty and finding out they are only wanted to tank all the time, Paladins become better in PvP situations making them attractive at higher levels although wanted to heal in raids, etc).
You guys?