Bo Pelini would be my guess, Kirk Ferentz would get my vote. Kill at Minnesota is also a candidate, he may be on the same level as his predecessor, and both are a lessor Glenn Mason..... and his seizure thing is concerning.
Indiana seemed to be improved, on the field last season. Illinois, Purdue, Wisconsin and State Penn are not far enough along in the regime, to judge.
Hoke and Dantoni have peaked their potential, IMO, but their peak is greater than the lower half of the Big 10, so they have that going for them.
Looking forward to the the new Big10/11/12/14, If I were Maryland I'd be looking around. Maybe they should pool some money together, to bring Rex Ryan back to the Terrapin Station after he gets fired from the Jets.