Miami '01?
FSU '13-'14 isn't close. I might even pick Army '45 over FSU '13-'14 based on what I've read, but I never saw that Army team play.
1971 Nebraska best team ever
That year, the final national polls had Nebraska #1, Oklahoma #2, Colorado #3....all from the Big 8 Conference
Not only 1971 Nebraska was the top team ever...the Big 8 that season may have been the best conference season ever