I'm in the same boat as you. I'm going with Jackson personally based on this:
I've had decent luck for the most part this season with rookie RBs (Nick Chubb, Kerryon Johnson) so may as well keep leaning on them.
Moved them here
Jackson is the #1 waiver add in my opinion. The Chiefs allow over five yards per carry, and if Gordon and Ekeler are out, I have no idea who else the Chargers have at running back.
Here's my quandary, if anyone is interested.
This league freezes add/drop moves and trades at the kickoff of week 12. (There is a limited number of roster moves available anyway.)
However, IR is still available through the playoffs (also a limited number of weeks available, but I didn't use mine so I'm good). But a player has to be on IR or have an O (out) designation to be able to place on IR and add someone in his spot.
To add Ware, I put Kupp on IR. My other players who will probably get the O designation won't get it until after Thursday's game, meaning I can't reserve them and add someone before Thursday's game. Unless I release Ware and put Jackson in Kupp's spot. But Ware would then be FA, so there's no surety I could re-add him for week 16 if I wanted to.
So I have three options:
1) As I just said, drop Ware and add Jackson.
2) Wait until one of my other injured players is officially declared out (after Thursday's game probably) and add Martin or Wilson.
3) Just play Peyton Barber, who's already on my roster.
Just to be clear, Kerryon Johnson was supposed to be the go-to guy if something happened to one of my starting backs.