Gay gang bangs, or just amateur guys' cumshots (the kind where they only film the last minute or so, and I'll just watch a bunch queued in a row). Outdoors/public stuff, too.
If I'm watching porn with a partner, I won't mind if there are girls in my porn, but ... I pretty much only watch stuff that's by guys, for guys who like guys. Seems strange, because I like women just fine in erotica, and obviously I'm in all of my own personal fantasies... but girls in porn usually are more distracting to me than pleasurable.