First off, I go to USC so I know a lot more about that program. In my opinion, if all you want to do at school is direct things then AFI is the better choice. If you want to take classes that focus on other areas of filmmaking as well then go to USC. AFI's program is specialized in directing. All of your classes are designed for directors. At USC, the first year you do everything (Writing, Producing, Directing, Cinematography, Editing, Sound, Production Design) and then after that there are only a couple of classes that are specifically about directing (working with actors), but most directors take Intermediate Cinematography, Editing, Sound, Producing, etc. in order to learn more about each department. USC's approach is more about creating a filmmaker who knows a bit about everything, which I personally love, but I know some people get frustrated because they aren't able to just direct all the time. So really, it's all about knowing yourself and what you want out of filmschool.