The question asks for an opinion which I think I can give without being discriminatory. My first mm sex was with a gay guy and he showed me what I had been missing out on for most of my sexually active life. I didn't plan it for him to be gay or bi, that was just how it happened.
Incidentally, my first mf sex was with a woman ten years older than me, and she again made it something to remember.
The common factor in these two sentences is experience.
I walked into a steam room and came out with cum all over me, not sure what if they were gay, bi or straight and married. Just shocked that a couple of guys made me horny as fuck and that was how my first experience went down. I was thinking it would be a lil more romantic, rather than slutty.