In general, I find both very incomprehensible, it's just for different reasons. Maybe it's just because I'm in High School, but I find that most women gable on about some new chick flic, or gossip about people I don't know or care about, or just something straight up stupid.
example: a Spanish teacher has gone on leave for the rest of the year, and the new teacher is much harder. Anonymous Girl: "Dammit! Now we're actually gonna have to learn Spanish!"
On the other side, men usually discuss the team balance in some sport, or the latest rap or some other crap I don't care about. However, I do find more intelligent girls than intelligent boys, so maybe that says something.