I'm not sure I can say someone is at the top of the list. From what I have read about Brent Key, I like him. And his background reminds me of one of our past football coaches, Jim Carlen, who I liked a lot.
Obviously, Jamme Chadwell, would be a great hire.
Another one to keep an eye on is Rhett Lashlee of SMU, which just joined the ACC.
If we have an opening at the end of the season, do NOT try to buy on the "cheap". That's what we did with nepo baby Beamer. How is that working out for us? If USC is serious about football, spend what it takes to get a quality football coach. If we are not serious about football, scale back in that sport and fund other sports. Hopefully, it won't come to that.