The AAC minus SMU sure is better than the Big 12. In fact, win % wise, even with SMU we are better. Actually, in most computers and polls, it will give credit to beating ranked teams, so if media bias gives Big 12 members the ranking prematurely, obviously their SoS will be inflated.
For an example, look how Texas rose to #11 for beating a terrible Notre Dame team. Now Texas is 2-3, as well as Notre Dame.
I would with 100% confidence say that top to bottom, the AAC is better