I agree with your comment, but other than BYU... yuck. City College of Cincinnati, City College of Boise, City College of Memphis, and City College of Houston don't help with eyeballs or interest. The Directional School of Central Florida doesn't help either.
Yeah, if the premise is you reform and don't all go separate ways, then there are not a lot of options available. Definitely none that are as good as what you lost or even halfway sexy. You're kind of building from scratch or basically doing the ACC approach of adding the Big East schools. The hope being you can rise win totals for enough teams to get multiple ranked opponents. That creates opportunity to perform in the post season. I mean, you don't have to beat Oklahoma every year to go 12-0. That gets you in the dance with a chance to win. Its likely harder to get that chance when you reside with Ohio State, Penn State, Wisconsin, Alabama, Oklahoma, Georgia, etc. Start a trend of competing and even winning in the post season, over a decade or so, and value will rise.
Now, everyone freaked out on Temple, and I agree, likely worst of those choices, but you want to be east, not west, and not for carriage on a channel you don't have, you want it for potential eyeballs and timing. Last I looked was like 5 years ago, but this was basically the percent of the population that lives in each time zone in the US:
East = 50%
Central = 30%
Mountain = 5%
Pacific = 15%
Over 75% from the Big 12 footprint east. That's why the Pac 12 wants to OOC match ups with the ACC/Big Ten. Someone implied that is changing, but for the western half of the US to catch up with the eastern, they'd need to add over 150m people, without the eastern half growing at all, to get relatively close Since the south is growing faster than anywhere else, that is highly unlikely.
Now, you do need good football match ups, agreed. Currently, UCF, Cinci, Memphis and Houston have all had the same levels of success as BYU, UCF and Cinci would rank 5th and 6th in avg audience (ahead of TCU/Baylor/Kansas), with AAC games in this hypothetical expansion. Those two are no-brainers and would have an increase in audience playing the Big 12 competition instead of the AAC.
So the question becomes, how do you fill in the gaps from there. Memphis and Houston drew just slightly less than Baylor did (still better than Kansas, if that's any indication on how bad Kansas has been). Do you need four teams in Texas? Maybe, that gives everyone at least one and maybe two games per year in the state that isn't from there. If you don't, the question is what fits next. You're already taking schools you're hoping to improve with increased match ups, who could you ratchet higher who isn't an outlier from that mix?
Temple - agreed, not the best choice, but is near WVU, resides within a top 5 population center, and is a state school of a football hungry state. When Matt Rhule had them rocking they drew very good numbers. They also provide you a base for OOC match ups between ACC/Big Ten teams in the area (Penn State plays them on a rotation with Pitt), which you'll want to exploit with WVU.
Tulane - likely the worst choice, to be honest. While LSU is the king in Louisiana, they have competition from schools like Louisiana or ULM who have done well too. This would be your Rutgers bet hoping you can get them to be in LSU's shadow, not Louisiana's. The benefit is New Orleans, which, like WVU, sets you up for more OOC match ups with the SEC. Ironically, Tulane outdrew Kansas.
USF - like the Houston conversation, if you're already going to Florida, should you go twice? The Tampa market is all Bucs, but its growing, fast. They're struggling but, like UCF, is sitting on a goldmine of talent and a gigantic enrollment, even if most is commuter. They're never going to be FSU or Miami, but that doesn't mean they couldn't be successful, and you could use it as a way to get more Florida players onto rosters (WVU goes there a ton)
Admittedly, none are home runs, but this isn't a home run solution. All of them, however, fill in the gaps between your 7 and WVU within growing states with a lot of population and talent. One of the biggest issues with the Big 12 is its population base, that has to be fixed. That means when good, audiences will be bigger.
Boise and BYU benefit from the MACtion efforts of ESPN, in that being successful on the weekdays get them more exposure, which in turn helps them be successful. Both of them only out drew Kansas and Tulane, even with the success they had. So attributing them a large fanbase is not based on math. Additionally, the last time the Big 12 even sniffed expansion, there was a ton of protests against BYU. The Big 12 has an inclusivity agreement between their schools and, while BYU doesn't have to agree to it and no one needs to make BYU do what they don't want to do, the other universities had them at arms length last time.
If you have to take this route, go with what you can grow. Not only in who you pick up, but where you recruit and what will get your good teams more wins. If you add UCF, Cinci, Houston, Memphis, you already have two top ten teams this year, with two (TCU, OkSt) right outside the Top 25. You could easily get 4-5 ranked teams a year with the success WVU, Kstate, Tech, or even Memphis/UCF/Houston tend to have. Going west gets you literally nothing.