I would take Gruden over any of the above mentioned candidates. His is a household name, and a prestigious one at that.
Bama was able to hire Saban away from the NFL. Hell, Arkansas was able to hire Petrino. Not that I think he would be as easy to get as those two, but in my opinion, he is more highly thought of than either, and has been there for a long time.
It wouldn't just be bringing in a coach with NFL experience, but one who not only coached, but was extremely successful at every job.
It may be unrealistic, as compared to Muschamp, but as compared to B. Davis? I couldn't say.
However, I'd take him over all the other mentioned candidates, with the possible exception of Bill Cowher (who I do have doubts about actually wanting the job). Those guys are hardly Lane Kiffin, Mike Nolan, or the guy who was Nebraska's head coach after Solich. They are proven winners.