If I were the King of all college football, my choice would be that BYU joins the Big12. I love their style of play and think it would be a great conference for BYU football and bball. Close second would be Pac12. But dont for one second confuse joining a P5 with "playing a tough Indy" schedule. They are worlds different. Joining a P5 means recruiting benefits, conference championship benefits, and money $$$, respect and prestige. BYU does not have those things now, they are not P5 in any meaningful sense. 

But I also do not believe that BYU will be invited to any P5. Not because they couldn't compete or dont have the facilities etc. I don't think any P5 wants BYU for other reasons, the same reasons that kept BYU out the past 3 rounds of expansion. The political/religuous aspect have only gotten more heated and more pronounced.