First, I'm eliminating all G5 schools from the consideration. Between the PAC and ACC, there are plenty of schools to grow the B12 uncomfortably large as it is. The B12 isn't trying to beef up membership to stay afloat, the reasons the schools that were added in 2021 were picked aren't the same as how schools would be chosen going forward.
Second, the "basketball conference" question, ie, Big East and Gonzaga. I really think that 9/10 Big East schools really like their set-up with a conference of religious schools that don't have a football program. UConn is the obvious outlier.
Third, eliminate the schools that the B10/SEC are going to snap up right away, are too "academically prestigious" for the B12, or some combination of the two:
Notre Dame, Florida State, Clemson, Miami, UNC, UVA, Stanford, Cal.
First Tier - schools that are pretty much no brainers. Yes, these are schools that might get picked up by the B10 or SEC at some point in the future. When they get an offer, they're gone, but until then, the B12 could profit off of them. Having them or not having them does little to change the B12's status as the #3 conference, particularly if the PAC and ACC cease to exist as power conferences.
Washington
Oregon
Duke (their basketball alone gets them close to B12-level value)
Second Tier - schools that seem to be a good fit for the B12 and would be long-term members:
Pitt
NC State
VA Tech
Utah
Arizona
Arizona State
Colorado
Third Tier - schools that have some good attributes, but I'm not entirely sold on:
UConn
Syracuse
Louisville
GA Tech
Fourth Tier - schools that don't really seem to fit. BC and WF would make a lot of sense in the Big East, and Or St, WA St make a lot of sense in the MWC (I'm sorry to say).
Boston College
Oregon St
Washington St
Wake Forest