I play a male character (same sex as myself) and I find much like you do that I can't really become immersed into the game as much when I'm playing a female character I just don't feel like it is really me being portrayed in the game that way. However if I'm going thru a game a second time I will generally pick a female character because at that point I want to see what it is like to be someone almost completely opposite from me go evil or screw someone over that I wouldn't have done the first time to see what the consequences were if any and also if new dialogue trees or other things open up not previously available to me as a male or good character.
On the other hand most of my friends play exclusively female characters saying their reason is that if they have to look at someone's ass all game they'd prefer it to be a girl's.
On the other hand most of my friends play exclusively female characters saying their reason is that if they have to look at someone's ass all game they'd prefer it to be a girl's.