I always roll a rogue/thief/ninja type character. I like high damage, high speed melee, and I like that usually that type of character has some way to hide or disappear (good for when the wife wants me to get up and do something or when the baby starts crying).

I think it's best to stick to one type of class, especially if you're like me and are a beta-test/free-to-play junkie. If you roll all different kinds of classes, you may end up not liking a great game in comparison to another due to comparing apples and oranges.

(I also pick rogues because I'm immature and like to say that "rogues do it from behind")