Newbie to the forum, but this applied to me and I'd like to offer my two cents.

I've DONE all four. With women, I'm equally happy to sub or Dom, and with men, I prefer to Dom. I've only played sub with my long-term (male) partner, and I'm happy to keep it that way. I've always leaned more toward women as far as my sexual preference goes, and while I do appreciate the aesthetics of bollocks and bums...I've never been too keen on the cock. c:

I also have a pre-op MtF tranny friend, who I have both subbed and Dommed with. c: Both experiences were thoroughly enjoyable, and certainly something to be repeated.