I'm not sure if I'm sold on the Saints yet. At this point it's clear there defense won't be as bad as it has been in years past, but I also think they have overachieved.
Panthers have the best defense in the division (Falcons have a good and underrated defense too) but also probably have the worst offense, although they can have their moments ie. Lions/Patriots games.
Buccaneers aren't that good.
Gun to my head, I think the Falcons take the division. They are the most balanced team. Panthers and Saints will be in the mix with the Rams/Seahawks (maybe the Redskins/Cowboys) for the wildcard spots.