Add Josh Allen as backup QB or Justin Jackson as backup RB?

Standard league team, short 5 player bench. I have Goff as my QB (used Jameis Winston last week fortunately). Goff has decent matchups (home vs PHI, on road vs ARI). But LAR may sit Goff on week 16. My RBs are Melvin Gordon (questionable), James Conner (questionable), Saquon Barkley, Joe Mixon, Philip Lindsey, and Sony Michel (and Jalen Samuels, but set at TE as long as Conner is out).

So here’s the question… should I drop Winston for Josh Allen (just in case Goff is rested or gets hurt), or for Justin Jackson (in case Gordon sits… but less likely to actual start him over Barkley, Mixon, or Lindsey, who tentatively are my starting RBs)?