It depends. In Dragon Age Origins, it was predominantly female except for the City Elf and Dwarven Noble origins. In Dragon Age 2, I've played both, but I prefer the male. In Mass Effect, it's female 99% of the time. Going back to Ultima, it was female until they forced the male gender. In Skyrim, my first (and so far only, at 300 hours) playthrough was female. Baldur's Gate was female.
Actually, I suppose I just go with the female option unless given a good reason to try otherwise. When the protagonists were silent and you were left to fill in the character's background and motivations for yourself, I went with what I knew, which was me. But for a game like Dragon Age 2, for instance, I just liked the way the male Hawke sounded for the way I played the game.