Barring a national championship this year, I think Dan Mullen has to be at the top of the list.
As for who is best for Tennessee: Florida deciding to shut down their football program, maybe?
Keeping Muschamp a couple more years is the best arrangement for UT. He goes 7-6, plays (overrated) FSU close, loses 1-2 top recruits to Jimbo, ends up with a >30th class again and then again.