If it were me, I'd go with the QB with the hot hand. Baylor beat Boise State. Baylor beat Utah State. He got it done vs. an underrated Liberty squad. His numbers are pretty darn solid. Watching the games, Baylor also seems the most dialed in with the WRs.
I think Zach will do great too but I don't see why not let the guy winning the games keep going and see if his play continues to improve.
This is a great problem to have by the way.