MSU's Rose Bowl pushes it over the top to me, but the late season chaos of the Kick Six to knock out Bama, then the Big Ten CCG to knock out OSU, to put an overlooked Auburn team in, with a great national title game. Particularly in the last year of the non-playoff, makes it easy for me.
Although I'm not totally convinced MSU's 2014 team wasn't their best. 12-2 with a NY6 Bowl win over Baylor, in a 20 points comeback, where the 2 losses were to the two NC game participants (OSU and Oregon)