<p>Well, Harvard and Princeton are Single-Choice Early Action, so it’s nonbinding and you pick one . However, UPenn is Early Decision, so if you’re accepted, you have to attend. The admission rate is probably higher, since you promise to go if they choose you. Basically, if you’re sure you’d be happy attending UPenn if accepted and won’t have any regrets if you don’t get to pick another school, go for Early Decision there. Otherwise, pick Harvard or Princeton. Also, look at regular Early Admission schools where you can get more early, nonbinding decisions. Does that help??
Also, these schools are pretty much long shots for everyone, so no one can say what your chances are because almost anyone (unless, like you said, those gold medalists and published authors) has pretty low chances.</p>