The only thing I'd point out about teams we'd play is you have to look at divisions.
I have two issues with the Big Ten. One, the weather would suck for a lot of road games. Two, if we join, it would probably be the West division with Wisconsin, Nebraska, Iowa, Purdue, Minnesota, Illinois, Northwestern, and we'd only get to play tOSU, UM, and PSU occasionally. That doesn't excite me much. I guess the third potential downside is OU seems the least likely to come with in the Big Ten.
The problem with the Pac to me is time zones, but the current Pac 12 south division includes USC, UCLA, UA, Az St., Colorado, and Utah. I like the prospect of playing those teams every year much better, from a football and road trip standpoint. We wouldn't have to play the less desirable teams in that conference, like Oregon State and Washington State, nearly as often.
Regardless, there's definitely not perfect fit at this point and since the Big 12 is the only one whose deal is up in 2022, starting super conferences probably wouldn't happen at that point.