If we're talking about games where you make a character, or simply choose one as an avatar, male. I'm a man and I prefer a male character to represent myself, and I prefer to stare at a male character for hours on end.

Unless we're talking about games where there's a selection of pre-established characters that you choose from. Then I tend to play as whoever has the best stats. In most fighting games I always tend to be better with female characters because they tend to move the fastest.