It's comforting to see that I'm not the only one who's put off transitioning in part because there's a wider pool of male partners when you're a man disguised as a woman than when you're a man. I have often considered myself lucky, thinking, "What gay man wouldn't want to be able to disguise himself as a woman in order to get straight guys?" Unfortunately, in my case, the disguise is permanent, which is not enviable. And of course there's more to life than pursuing partners. When I take sex and relationships out of the equation, I definitely want to present as male.
I've had a different experience with relationships than other people who have posted, though. The boy brain / girl body does work for me in relationships. I seem to naturally gravitate to guys who see this as a good thing, or guys who just like me for who I am, regardless of gender identity and gender expression.
My current partner seems to truly have a preference for male brain / female body, and we balance well together because in some ways, he's like a woman in a male body. Superficially, we take on traditional gender roles - he likes to pay for things, fix things, lift heavy objects, etc. But he's femme in his mannerisms and way of thinking (if I try to describe it, it just sounds like a list of gender stereotypes, so I won't go there), and the things he admires about me most are more masculine traits: boldness, ambitiousness, determination work ethic, ability to keep my emotions in check, etc. He just accepts me for who I am and I accept him for who he is. It works for now.