As much as I hate Ohio State, they are one of the four best teams in the country. The four best should be in.
The Danderoo was something else. How he went all those years without whipping Cossell's ass in the booth escapes me. Rumor has it, he had a beverage or two before kickoff. I believe it.
I prefer to use BCS ratings, but we're married to the bullshit playoff rankings. The top 2 ranked teams get in. Any conference (BCS/nonBCS) champion from a conference not already represented in the top 2 is considered. The highest ranked champions get the remaining spots as long as they are ranked in the top 8. If any spots are open, the highest ranked teams whose conference is not already represented gets in. This places value on ranking, but also places value on conference championships and diversity of representation (to combat inflation of rankings based on perception, which isn't always reflective of reality). So if Ohio St is top 2, they're in. If not and the B10 champ is top 8, they're considered with other conference champions.