In recent years I've come to respect Michigan a lot more. The state, the university, and even the university's football team. I've lived in Columbus my whole life, and I've even been an Ohio State student. But I'll root for the Wolverines, as long as they aren't playing the Buckeyes. Which they are, today. Today, I want to see Michigan lose. But I can't bring myself to say bad things about them.
How I decide who to root for
S: Ohio State
A: Michigan
B: Any other Big Ten team
C: Any team not in Big Ten or SEC
D: Any SEC team other than Alabama
F: Alabama
Note that I don't go out of my way to watch a game unless Ohio State plays in it, though sometimes I'll look up how Michigan did after their game.
S: Ohio State
A: Miami U (Ohio); Notre Dame
B: Any Big Ten team other than Ohio State or Michigan; sometimes Michigan if they're “representing the Big Ten” in a bowl game
C: Underdogs, sometimes
D: Any team not listed above
E: SEC teams, sometimes
F: Michigan, usually
Disclaimer: I kinda put Mom on the spot with this, and she didn't want to put a whole lot of thought into it. Who she roots for is often quite situational, and may be difficult to determine in advance with something so simple as a tier list.