1) Jim Bob Cooter. I'm BANGING THE TABLE for this guy. Seriously. He seems to have worked out the fumbling issues with Ameer Abdullah and is using Theo Riddick almost like Marshall Faulk. Dude's basically a WR out of the backfield. But MOST importantly, Matthew Stafford looks more confident and on point than he's looked...maybe EVER. I only had to see the one game to see that he just looks...different. Maybe it's because I had such low expectations, so the massive differential biases me. That's possible. But even with that... there's that massive differential. Without Calvin Johnson, Matthew Stafford has this team looking like world beaters...on OFFENSE. Granted, they were playing Indy, iirc, which isn't saying much, but still. JBC is the guy if I had one choice.
1A) If names matter and there is the slightest PR concern (which there shouldn't be, but meh), then the 1a choice is David Shaw. The fact that he got Stanford, a private school with exacting academic standards to compete on the national stage with schools that treat the moniker "student athlete" as a snide joke is nothing short of a miracle. He's already showed that he can develop QBs like Andrew Luck and that he can go with a power running game when that's who he has. He believes in winning in the trenches and he understands solid, defensive football. He also is a very good teacher when it comes to the secondary. He's an all around fantastic HC that I'm SHOCKED isn't an NFL HC and I fully expect that he'll be in the NFL in 2017 if the right job *cough* LOS ANGELES* *COUGH* opens up.
After that, imho, the list starts at 4. There's no one really close to those two and that includes candidates like Todd Haley.
And no, Jim Harbaugh isn't leaving Michigan. It's his dream job and you don't leave your dream job to do the crap in the NFL again. Never say never, but I wouldn't bet he comes back to the NFL any time soon.