I honestly don't think there is much separation in the Maryland, Purdue, Minnesota, Rutgers, Illinois, Indiana tier and I also don't think that group is far behind the Michigan, Northwestern, Iowa, Nebraska and maybe even Michigan State group. Wisconsin, Penn State and Ohio State have put some distance between themselves and the rest though I am not sold that Wisconsin is all that dominant. Best in the division but don't really see them as a realistic title contender at this point.
Ohio State vs. Penn State this weekend will be really interesting. Outside of the egg they laid against Oklahoma, Ohio State's offense has been unreal and Penn State has looked really strong as well. I would say the winner of that game is the clear cut favorite to win the conference this season.
Penn State, Ohio State, and Wisconsin have put some separation between themselves and everyone else.