Well.
Death knights will still be super boring. No real changes at all. Necrotic strike sucks. GG 1/5 of a heal absorbed.. is that a replacement for MS? Heh. Dont level this one up.
Rogues, seems to be alot fun with their new skills. But the talent trees havent changed much. I wouldnt level rogue up.
Paladin might be fun. Looks like shockadins gonna be alive again for some weeks
New mechanics etc, i would level this one up for sure but as an alt.
Druid seems the most fun. Troll druid, lol, moonkin with mushrooms, solar beam etc. If i were you i would level this one up for skillz good lookings and alot of fun.