We both know that he is a female biologically, but even looking at him naked, the overall picture says man. Until you get to the genitals. It was very confusing at first because you are looking at someone who looks completely male, other than that part, it doesn't even register with me anymore though. I have been with men with a whole range of penis shapes and sizes, now one with a vagina.
I can not look at him and see a woman, I have tried. He looks like a man.
I am not attracted to butch lesbians, or androgynous people of either sex. I am only attracted to people with a male body shape and face and the lack of penis doesn't put me off.
So to fit myself into a category I would say straight, because there is more to attraction than gentitals, I am only attracted to male presenting people. (Is there a sexuality for that?)
(All whilst knowing he can never switch sex, I am not denying that - just that for me personally I am happy to date anyone convincingly male.)
I personally wouldn't date a trans woman. Hypocrite eh!