Tut tut JohnWesley. Since when has downtown LA been the middle of nowhere? My s may be headed to Wes, but I must stand up for my town. True the train station, it is a corner of downtown, and true downtown LA is probably not the most interesting place for college kids (Staples Center aside), still, in the middle of nowhere is certainly not true.
To the OP, USC is a very different environment than the other two on your list which are liberal arts colleges. You need to decide what you want -- smaller classes, with a more intimate educational experience, or a larger university with D1 sports and a 9very0 big greek scene. If you decide on smaller, I'd have to agree with the poster that CMC has the stronger reputation.