Waiver defense help

Would you use your top waiver claim (does not reset each week) on a top defense for this week such as Dallas (or the Panthers?) or wait and pick from likely tier 2 - MIA, NYJ, TEN?, KC? And hold the clam spot?

If Bethard doesnt play, could look at Oakland as an under the radar play as well. Leaning towards waiting, but need upside from defense with a lot of byes this week.