Male playing female.
I wanted to play Warrior and Druid on the Alliance side, and play them at the same time, so I had to be Night Elf.
I didn't want to have the huge NE male models taking up screen real estate, especially given that I'm looking at 2 clients at once.
I chose female avatars because honestly I don't think it matters for anything other than my personal experience with the game. If people want to assume I'm female that's fine, I will correct them if I have to but otherwise their assumptions are their own.
Never stop never stopping.