Yes, the SEC is better without question, as a whole...but name the quality SEC West wins. Name the quality Big12 wins. You're going to find that it's similar to the Pac12 when you look at them individually.
For the most part, those 3 conferences have beat up the other 2 in the P5...and won most of their OOC games, even if it's vs. teams that for the most part aren't considered "great". The top 5 teams in the Pac12 South have a 13-1 OOC record...and you can only beat who you play.