College Auditions: Should I play...?

You need to play the one that you play the best. Both are contrasting pieces and if you have enough time and know them both well enough to perform, go for it.. If you are auditioning for a scholarship, play your best work. When I auditioned for my scholarship, I played Hindemith. It showed off my technique and ability to play complex rhythms. Bone up on your sight reading too. They might hit you with that as well.