I'm gonna say
AFC
Patriots or Steelers, though I'm leaning Patriots, even though the Steelers beat them, I don't think they will do it again.
NFC
As Supra said, Eagles have no competition, getting to the Superbowl is cake. Beating either New England or Pittsburgh is not cake. And Pittsburgh has beaten them already, but that is by no means a guarantee they can do it again, just like with the Patriots.