Ouch. If it's any consolation, you're more or less screwed either way, so it doesn't matter much.
I'd suggest trying to make a waiver wire grab. If your league isn't very active Stecker (NO) might be free, or someone else decent.
If it's absolutely down to those two, AP has a lot more upside than Kobly. Kolby's done basically nothing since the one game against the raiders, and my grandma could get 120 yards and a TD against them. While it's a longshot that peterson does well against Minn, it seems more likely than Kolby doing well against the jags.