I prefer mostly black clothes too. I like the uniformity of it, and how it leaves nothing to be focused upon. It reduces all "style" to just outfit.
As soon as colors come into the picture, you begin to make statements, "ORANGE! CUS I LIKE ORANGES!!!"
Gray is also acceptable. Sometimes I wear all gray. Like a cloud :0
Not as a rule tho, I wear whatever is on top of my clean clothes piles, but most of that is dark colored