I'm inclined to pick the Saints. Their offense is as good as any in the league. Their passing game is on par with the Pats passing game while I think they have better depth and talent at the RB position. Defensively it's about a wash though I think they have a few more playmakers than the Pats.
Despite their records and success, I can't pick the 49ers or Ravens based simply on them having non elite QBs. (Though I think the Ravens match up favorably against the Pats).
So I'd have
2. Saints
3a. Steelers
3b. Patriots
5. Ravens
6. 49ers