Hmmm... I find that strength is critical before gender. In general I'll bottom for a man and Top for a woman, but the other two can and have happened-If I consider a male partner physically weaker then I wouldn't be comfortable subbing to him. Meanwhile my preference is for subbing to a woman but I have to be convinced of the other person's power over me, and that's just so much more easily accomplished with a man. It takes a little extra for a woman, but when it has happened there's nothing better.