Paladins and shamans.
Pallys lost me because I hate blood elves and that was the only option until recently. When Taurens get reskinned I might give them another try.
Shamans lost me because they just seem goofy with their little totems and lightning balls.
Everything else I've taken to 90. Out of the classes I have at 90 I have to say the Mage is the most disappointing. I hate frost...love fire, but absolutely detest frost and it's the only viable spec these days so my mage is sitting at 90 this expac.