It's just a preference, like sex is a big part of relationship compatibility. Trans people's feelings really aren't hurt by either, generally. The only time it's really a problem is when it's based on the femininity associated with trans masculine people and the masculinity associated with trans feminine people through stereotypes and whatnot, or the way trans people's bodies are stereotyped as inherently wrong/gross/unattractive.
it's maybe something you want to think about, is all. If a trans man passed extremely well, and you wouldn't know he was trans at any point unless he told you, and you still wouldn't date him (ex. cause you don't think trans men can have proper facial hair or something, and you like guys with beards), then it might be worth considering why you think that, or if it's true.
there's better examples out there, i just can't think of any right now.