(1) prestige and (2) the amount of influence it will have.

They will consider payout but they have more money than they can spend no matter the outcome. I think ruling out any possibility, including independence, is short sighted.

B1G offers academics and athletics. But B1G doesn't help their recruiting and OSU, UM, and PSU are equally big dogs. They won't defer to Texas for anything. [ and while I downplay $$$, Fox could throw the house at them to try to tip the balance of power away from ESPN]

SEC offers football prestige (and staying on ESPN) and expanding their recruiting footprint further into the fertile southeast. But again, there are equally big dogs and academically, it's kind of where they are now.

A PAC 12/Big 12 merger solves a lot of political issues for the Big 12 and state of Texas in particular. And UT would be a major influence peddler. California is great recruiting territory and Austin is basically a little piece of California with great BBQ.

ACC has academic prestige and offers them the best chance to keep LHN (think ego). If they join hand in hand with ND (going in full), they will be instant royalty. ACC has the largest broadcast footprint as well and like the SEC, includes fertile recruiting grounds.