The SEC has been called the best conference in college football. With seven straight national championships under its belt, it's a tough argument to counter.

The Pac-12 might have it beat in terms of depth.

From the national championship contenders at the top to the rapidly-improving teams at the bottom, the Pac-12 may be the nation's deepest conference.

The Pac-12 has three undefeated teams — Oregon, Stanford and UCLA — and four in the Top 25.

But what has made the conference so strong this season is the improvement by Washington State, Utah and Colorado.

California, 1-4 in its first season under coach Sonny Dykes, is the only team in the conference with a losing record.