FWIW I went with the Titans this week. My 'leading indicator' I primarily use for defenses is sacks. Not only is there a direct relationship (sack=point) but getting after the QB leads to INTs, and leads to defensive touchdowns.
They had 8 sacks last week vs Colts (FWIW Colts are now #1 in sacks allowed with 47, leading the pack by 7). Houston (who Titans playing) are 8th with 34, not that stout of a line.
Link to data if interested
http://www.espn.com/nfl/statistics/team/_/stat/passing/sort/sacks
So I just took the top 8 teams in sacks allowed (after 8 it drops off a bit) and examined each. My picks to consider:
Steelers / Ravens / Bears / Titans
Indy vs Jags (Jags likely unavailable)
Packers vs Bucs (Bucs dead last in sacks for the year - pass)
Bengals vs Steelers (Steelers unavailable but good choice if so)
Broncos vs Dolphins (Dolphins 3rd lowest sack total - pass)
Lions vs Ravens (Unavail for me, but could be good choice)
Jets vs Chiefs (Defense hasn't been great...unavail for me anyway)
49ers vs Bears (Decent choice...unavail for me)
Texans vs Titans (Middle of the pack but have improved as season gone on - avail and my choice)