Too many good RB's. Who do I bench?

[Sammy Watkins' Rib]

So I have McCoy, Gurley, Elliot and Collins. I drafted McCoy and Gurley 1 and 2 and picked up both Collins and Elliot a few weeks ago. I have to bench one of the three. I was leaning towards benching McCoy earlier in the week in favor of Collins easy match up against the Colts. Now I am thinking of reversing that. I think Elliot is a must start. Same for Gurley despite the tougher match up.

[CommonCents]

Ravens will be running the clock out. Bills will be passing to catch up. Start Collins IMO

[KD in CA]

I have a similar issue.  Gurley and Kamara are must starts, and Jordan Howard seems like the pick for my flex spot, but he's been disappointing lately and I have D Lewis on the bench.    How likely is it he lights up the Bills on Sunday?