we like to watch trans porn every so often but we never once watched FtM porn.
just not the same appeal what so ever imho, most str8 girls are turned on by a hot looking female body,
most str8 guys are turned on by a huge cock, no matter what both might say lol
MtF give both of a us what we like, with an added bonus, in the case of FtM, we'd only feel like something is missing :/
that being said, i think MtF porn is more aimed at "str8 curious/open minded", where FtM is imho more aimed at "Gay but not 100%" people, but maybe i'm mistaken tho :/