For me going 4-0 and still missing the playoffs would be the most painful for them.
With that said, it depends on who the two losses would be. Lose to Arkansas on the road, where they have not played well and Georgia at home, where they may not be favored, it would suck but not the most painful. Lose to Georgia at home and MSU at home (I'm aware the second loss here is not very likely) would be far more painful for them.