I like a nice wood finish. All-black speakers make me think "$30 Sony", as really cheap speakers are almost always black. Plus you have to dust black things twice as often as any other color. Dark woods (Walnut, Macassar, etc) are almost as bad, plus being really dark makes them look really small.
Light woods are a little better, but if they're too-white, then they look sun-bleached. Quasi-light to medium woods are good. (say: light oak -through- a dark cherry).