To me the main factors in USC’s favor would be smaller class sizes and more personal attention than at Berkeley. I do think Berkeley is a great place for grad or professional school, but it’s not all that different than other good state flagships for undergrad.
I heard someone once describe Cal following a “self-motivated educational philosophy”, which is a nice way of saying that if you’re a student, you’re pretty much on your own. Some students have no problems with that, while others have a hard time with it.