SEC is now the best conference with the Big 12 second
BUT before that (to 1994) the Big 12 was hands down the best. While each conference has 5 NC's since the Big 12 came to be, the Big 12 has had 4 seasons with 4 teams ranked in the top 10 (AP) and 3 seasons with 3. Not even the SEC can say the same.
While the SEC is on a great NC run, the Big 12 won 4 between 94-00.