There are different ways to look at which college football conference should be dubbed "the best." They typically vary on who you speak to on the subject, but normally championships reign supreme.
The Southeastern Conference owns eight out of the last 10 national championships in the sport, with four of them won by Nick Saban and Alabama, including 2015.
The lone Big Ten National Champion in the last decade is Ohio State. Urban Meyer and the Buckeyes took home the first-ever College Football Playoff National Championship in 2014, ushering in a new era in the sport that included a final four bracket and did away with the 16-year Bowl Championship Series model.