usc because its pbl and thus you have ****load of free time. do you know why usc has one of the highest average on the part I board? they have all the time in the world to study for it.
tufts, on the other hand, is totally opposite. you study with med students and study materials that are not even going to be tested on the boards. some say how every part of the body is connected to the oral cavity and you treat the person as a whole and yaddi yaddi yadda...bottom line....you'll suffer in tufts.
go to usc if you can. trust me.