I'm sorry, but it's not exactly just biased SEC fans saying the SEC has the best atmosphere. There are countless articles that all affirm the same thing. It's no coincidence that in ESPN's college stadium rankings (along with Sportis Illustrated among many others) 3 of the top 4 are SEC stadiums that hold 20-40 thousand less people yet are still twice as loud.
What's the nickname for Michigan's stadium outside of Ann Arbor again? Don't they call it the quietest 110,000 people on the planet? I've been to several big games (rivalry games) of top teams outside of the SEC, and also talked to many fans of other big name teams that then came to school down here in Florida and went to a big SEC game and couldn't believe what they were seeing.
Those type of games have great atmospheres, and I know that teams like Ohio State, Texas, Nebraska, etc have storied traditions and great atmospheres (hey what else is there to do in Ohio or Nebraska
) but until you've been to an SEC rivalry game, you really just don't know what you're missing. It's not even necessarily something to be proud of (I mean a part of it is just that there's plenty of drunken hicks from the trailer parks going absolutely nuts...which isn't necessarily a good thing), but it's just the way it is.