I'm biased towards USC, but I went to UC undergrad, and the budget situation means UCLA's funding is going to be cut and tuition is going up—as it has every year for the last while, by a lot. UCLA is a large state school and that atmosphere trickles down more to the law school than USC's, which is very small. UCLA does some annoying things like blocking wifi access during your scheduled classes.
If you want LA, go to UCLA or USC. Visit both, see their classes, and decide which you like better. There's no other way to do it.