Using end of last season KenPom ratings and estimating win probabilities - it looks like Houston has the "easiest" conference schedule and BYU is second. The "average" Big 12 team would expect 10.7 wins with Houston's schedule and 10.4 with BYU's.
Here's detail for every team. If you look down column it represents the games that team will play during the season - blue are games they are scheduled to play. Most difficult games are at the top and easiest at the bottom.