if it was a full PAC membership and there was no hint of potential discrimination against us in the future by it's ultra-liberal members, the PAC is clearly a better place to be.
If the culture differences aren't going to be a huge issue (and I'm certain they would be), sure, go to the PAC in a heartbeat.
Geographically the PAC is the best P5 representation of where LDS members in the US live... may not seem like a big deal, but it kinda is.
I also don't think BYU would mind being an independent again as long it had secured scheduling agreements with the PAC, BIG12, and/or the BIG10, a tie-in to their bowl-games, and NC-playoff game access. In fact if these things were true I don't think we have any motivation to join a conference. But they aren't true, and right now it's join any P5 conference or die.