Ranking sports teams is inherently difficult. What is a ranking supposed to mean--the best team right now or the most deserving team over the course of a season?
The best way to rank teams is by playing a long season and declaring the winner to be the league champion. This is how it's done, for instance, in European soccer leagues. There are 20 teams in England, and they each play every other team for a 38 game season. Whoever finishes on top after the season is the champion. No playoffs, no Super Bowl; a team proves it's the best over the course of the season.
Baseball used to do this, before the playoffs were expanded. Now, mediocre teams routinely win the World Series while superior teams lose in the playoffs.
As I noted before, there's always lots of complaining about college football rankings. I don't think they're perfect, but given the nature of the system (120 competitors, each playing 12 games) they're pretty good.