I was really surprised when I first came on this site by the number of straight couples who use strap ons for pegging. Harnesses and strapless were always a lesbian thing in my mind. Prior to being on this site, I would have thought there were more lesbians using them than straight couples but by now I have to say, I think there are probably a greater number of straight women using them on their male partners. This, as others said, is speaking strictly in numbers. Percentage-wise, I think the trans men would win, followed by the lesbians. Though, as a lesbian, I've met a surprising number of lesbians who have never used a strap on, on either side of the equation.