Ideally, I would like to be surprised but, as others have pointed out, when you are going into the game with the real possibility that you may have zero choices, I need to know before I buy the game. I won't but any game that includes romance mechanics but only hetero options; even a Bioware game. I only recently got into SWTOR after years and years because they finally pulled their collective finger out their asses and included an m/m option. Now we have 2 (Theron and Koth) and they're both companions now... not just NPCs like Theron was before.
To be honest after playing a gay man in games that allow it, I'm loathe to play any game where I'm just some straight dude for the millionth time. Even games like Uncharted which I used to enjoy just grate on my nerves with all the lovey-dovey crap (and subsequent marriage) between Nathan and Elena.
I doubt we're gonna see many AAA titles with a gay protagonist (if the story is set) so I wish there was some choice you could make at the beginning: Choose male or female and then either "Hero gets the girl" or "Hero gets the guy". I don't know if that would require 4 protags or just 2. People might freak out about story integrity if the same guy or girl could be so flexible. I just think it would be a really cool idea and I would pick it up in a heart beat.
I like romance content but it's not the romance itself that makes me buy the game it's being able to play as a character that I would aspire to be. I don't wanna be straight so walking in Nathan Drakes shoes isn't as much fun for me as being Shepard or Hawke. I guess it's the same for women who don't like to (or outright refuse to) play games where they cannot play as a female.
Sorry back on topic... I would like to be surprised and if it was a certainty that I would have options I would avoid all that but as it stands I can't.