How many Oxbridge applicants isn't really a measure as to how good the school is, is it? And even then, there isn't that much a difference between the two.
If you're more comfortable with your friends, and the teaching and stuff is good enough at the worse school, then go there.
If you work harder at the worse school then it doesn't matter, you'll still get the great grades you need to go wherever you want.
Can you do taster days and such, because if you really hate the worse school, then I'd suggest the better even if your friends aren't there. If the worse one is still nice, but the better one is slightly better for you, then I think judging by your responses you could go to the worse one and still do well.
However if there is a large difference in quality of education (you make it sound like both are good, just one's a bit better) then I'd say go for the better one, if you're aiming high (like oxbridge or something).