I'm a gay ftm and my husband is a gay man. I've talked to several gay (bio) men and I get mixed results. There are certainly people who prefer a certain genital configuration. I've met lesbians who are in long term relationships with pre-op and non-op trans women, I've talked to gay men in relationships with pre-op and non-op (bottom and top surgery) trans men. I've talked to people in both groups who are attracted to trans people and can't get over the genital stuff. I've meet hetro couples and people who are both ways.
It's confusing. I agree. For my relationship I can say this: my husband is gay. He is attracted to men, he prefers men and their biology and he loves me. I lack the genitals in the conventional sense. We've talked about it extensively because I didnt want him to be unfulfilled or repulsed by my physical reality. He views me as male. After top surgery the main characteristic is gone. He was attracted to me before because who I am, but the breasts got in the way for both of us. He dealt with them because it was a small thing compared to the whole. Now that they are gone, I've noticed that he can barely not express interest.
I asked him about this because I was worried that it would be that way with bottom surgery and here is what he said: "I'm more attracted to you now because I can see you as being happy. You're a man and you're happy. That confidence as a man is what always attracted me to you, even when you lived as a woman. But now you're so confident it's irresistible."
I define sexuality like I do gender. It's fluid and confusing. Are bigendered folk less because one day they feel like one gender and then next the other? (I'm not trying to insult the non-binary here, I just don't how else to explain it.) I have a gay male partner who looks at me and sees a man. I don't have "a dick" in the traditional sense, but he looks at my genitalia and sees a penis. One of my dearest friends is a lesbian and she's in a fairly new relationship with a trans woman who is pre-op and will be for the foreseeable future. Stephie said she sees her girlfriend naked and she sees a beautiful woman with nice breasts and a vagina.
I know it's not a clear answer, and I guess that's my point. There isn't one. Sexuality is confusing and at some points odd and make no sense to those outside the relationship. What I can say is that no two relationships are the same. Mine and my husbands relationship isn't the same as my parents relationship, my best friends relationships, my brothers polyamorous relationships. At the end of the day, does it matter how someone else lives happily?
Your sexuality will be different from every other humans. Your relationships will be different.
I wish I could explain it better, but hopefully that made some sense.