i suggest just play one you think you may like to lvl 20 and if your not entirely sure roll another class and do the same.
a class you think you will like may end up and boring you and vise versa.
the best advice i can give is don't worry about hitting max lvl asap
Just enjoy the game and when you are comfortable with your class/race choice get to 80
i also suggest ignoring what people say like "hunters are for retardeds" or "locks are for scrubs" just play what you enjoy and the opinions of other people won't mean squat.