Speaking to the top-heavy Pac-12 vs. more balanced B1G:
Number of times ranked in the final AP 2007-2011
Pac-12 (16): Oregon (5), USC (4), Utah (2), Stanford (2), Oregon St. (2), AZ St. (1)
B1G (22): Wisconsin (4), Ohio St. (4), Nebraska (3), Michigan St. (3), Penn St. (2), Michigan (2), Iowa (2), Illinois (1)
So the Pac-12 has their two elite, a Utah team that may or may not have been in the rankings (at least in 2009) had they been in a better conference, two teams that had a good couple years surrounded by losing seasons and one random.
The B1G has two elites (over this time period), two other Top 10 finishes (Iowa & Penn St.), three solids (NU, MU, MSU) and one random among 8 of their 12 that have finished in the Top 25 in just the last 5 years.
Advantage: B1G