Playoff DEF. Have P steelers

I have pitsburg as my defense. Who should I aim for the playoffs? For free / waiver right now: KC, NE, Cinc, Carolina. Also which weeks would you play them?

NE is getting better and has great 14, 16, 17 matchups. Only problem being you have both defenses for their week 15 clash. Chicago has the Browns week 16 which is juicy.