I guess it all comes down to, what you are going to choose to promote, I don't know anybody who promotes 10 different niches. So, I doubt any of the above replies would really help you in deciding what to promote.

Ofcourse, the best the thing is to choose the nitche you like best and promote it. You'll be mostsuccesfull at that.

I'm only promoting studs and jocks so I can reply, these two do the best for me, but only because I?m not trying any other nitche.