Caldwell would be the safe pick that no one could really say was a "bad" choice. I think Khan is more about marketing than that, though. For some reason, I think Leftwich is going to be at the top of their list since he's "a face". OC for the rival Florida franchise, OC for Tom Brady and SB Champs, former Jaguars starting QB. Sadly, diversity hire is marketable too. I think it'll be too much for him to pass up unless Leftwich bombs the interview.
Personally, I'd give the job to Pederson but I don't feel too strongly about who they get.