The SEC's best argument is the number of teams they have that are legit National Championship contenders at least once in a while. They have 5 teams (Alabama, LSU, UGA, FL, TN) that have won NCs in my lifetime, and a 6th that went undefeated (Auburn). A 7th team, Arkansas, though not in the SEC at the time, did compete for an NC during my lifetime.
The Big 10 on the other hand has only 3 teams that have won NCs in my lifetime. (
OSU, uknowho, PSU) The only other Big 10 team that I recall having had a #1 ranking was Iowa, and that dream ended in the month of October (nevermind the way they embarrassed the conference in the Rose Bowl).
EDIT: alrighty then - just finished my first cup of coffee and now remember that
OSU, in addition to ending Iowa's stay at #1 in 1985, also toppled Wisconsin and Purdue from the top-perch back in the 60s (yes, in my lifetime). Now that I think of it, Illinois was ranked #1 at some point during Dick Butkus' time there. None of these teams have competed for a NC all the way to the end of the season at any time in the last 40 years though. Damn I'm getting old.
But to suggest that all 7 (OK, 6 really) of the SEC's potential title contenders are at that level every year flies in the face of the facts. While Iowa, Wisconsin and several other Big 10 teams are not actual title contenders (or at least haven't been), they have matched up quite well with the SEC teams they've faced in the years that they faced them.
So while the SEC has more
programs that have NC potential according to the historical record, their collective power in
any given year has not proven to exceed that of the Big 10.