My first reaction was Amherst for the reasons that Lindagaf suggests – smaller school so easier to meet profs. But, otoh, I’ve never been sold on the Consortium: ‘as my son asked me when we toured Amherst, why would anyone pay Amherst tuition to be able to take classes at UMass?’
I’d drop USC as it is full of CA premed gunners who likely already have many research opportunities locked up. Sure, the same can be true at Penn, but I’m guessing that 'SC is just a tad more competitive in that area.
So, IMO, that leaves the OP with two academic choices (of admitted): Emory and Penn, but not necessarily in that order.