I personally like the Wizard and Barbarian a bit more than the rest of the crowd, i am probably going to do my first playthough or you know one of many but my first char is going to be the Wizard probably.
Witch Doctor (This would be my second character, if not because the Witch Doctor, looks soooo ugly (its hard for me to get attach to characters that look this ugly))
And then finally the Demon Hunter, i dunno i really think is great class but never ever have digged much on "archer", "rogues" "assasins" classes much.
If only the Necromancer were here though, that would absolutly be my first character, and as i like it so much would probably even neglect playtime on the others.
Ive always loved Necromancer classes, its my favorite type of class ever (i really dont know how they could have axed this class, well probably to have it as a HUGE SELLING point for future D3 expac, see what you did there blizzard :P); liking guild wars 2 a lot because its going to have necromancers ! :)