First, I always root hard against the Steelers, Patriots, 49ers and non-Dallas NFC East teams advancing in the playoffs.
Beyond that, I tend to root for teams that haven't been to the SB (or, failing that, teams that haven't won one) to get there, and I tend to favor the NFC team in the SB.
So for this year, I'll be rooting against PIT, NE and WAS in every game.
On the NFC side, I'll be rooting for CAR, ARI and MIN.
On the AFC side, I'd be perfectly happy to see any non-PIT, non-NE team make the SB. Most of them haven't been there in a very long time, and the most recent one (DEN) has Ware.