The SEC and Big 12 is very equal this year. Lets compare.
Big 12:
Top 6:
Oklahoma, Texas, Missouri, Texas Tech, Oklahoma St, Kansas
Bottom 6:
Kansas St, Colorado, Nebraska, Iowa St, Baylor, Texas A&M
SEC:
Top 6:
Alabama, LSU, Georgia, Florida, Vanderbilt, Kentucky
Bottom 6:
Auburn, South Carolina, Ole Miss, Arkansas, Miss St, Tennessee
Here's how it would play out on a neutral field amongst the Top 6: (in my opinion)
Oklahoma/Bama - Oklahoma (Very Close)
LSU/Texas - Texas (Very Close)
Missouri/Georgia - Georgia (Close)
Florida/Texas Tech - Florida (Close)
Oklahoma St/Vanderbilt - Oklahoma St.(Not so Close)
Kansas/Kentucky - Kentucky(Close)
The Bottom 6 could go either way.
So the SEC could be 12-0 or 0-12 against the Big 12, and the Big 12 could be 12-0 or 0-12 against the SEC.
Both conferences are pretty much dead even this year. Neither has the advantage