9 of the last 12 AFC champions have been from either the AFC East or North, and 6 of the last 12 Super Bowl winners have also been from those two divisions.
This is misleading, because 8/5 of those 12 winners have been either the Pats or the Steelers. Meanwhile, the Bills and Browns haven't made the playoffs, and the Bungles, Dolphins, and Jets have only made it a few times between them.
In the AFC North, you've got the Steelers and Ravens at the top, and while they might decline a little due to age/injury it shouldn't be too significant. The Bengals and Browns have the potential to be decent, so they get my tabs for best division. It's not often you see three playoff teams from one division anyway, even if the Bengals got the gift of scheduling last season. After that, I'd put the NFC North because the Lions and Bears should improve on where they were last year, and many people forget how the Bears were in prime position to take a wild card spot until Cutler/Forte got injured.
The NFC East was an embarrassment last year, Yondie; thanks to scheduling, they had the potential to have 3 playoff teams, and it blew up in their faces. They went a combined 1-7 against the NFC South and NFC North, the only win being Dallas against Tampa Bay. Only the Giants had a winning record against the AFC East, whom they swept, while they went a combined 9-7 against everyone's favorite tab for "worst division", the NFC West. Combined, that's 10-14 against the rest of the NFC.