I despise the whole ridiculous voting system to the core, but I'd probably give the third slot to Utah.
I am unaware of Utah's nonconference sked, but programs that go undefeated should do better in the polls than programs that lose to a team that is getting stomped on like they're Vandy or Temple.
I'm a Longhorn fan, but this Oklahoma meltdown doesn't make them look too good, either.