Which Defense To Drop?

Eight team league and we play TWO DEFENSES. Crazy I know, but that's the way it. Been playing musical chairs with defenses all year long, and will probably continue to do so. Holding 3 defenses right now: Denver, San Fran, & Dallas. Both the Coboys and 49ers are on bye, so I have to drop one of them. I will be picking up the Jags D because they play St. Louis at home. And the Rams offense certainly cures all that ails.

So do I keep:

Dallas

or

San Francisco