TWO questions. Really stumped

Really need your help fast here footclan. I have 3 running backs to consider for ONE spot.

Hyde vs SEA
Perine Vs NYG
Ajayi vs CHI

I can only start ONE of them.

My second question might be a no brained, but maybe not. I have Gronkowski (no brainer, right?) but I also have Vernon David against the NYG today. Who do i start? And if I start Perine, do i bank on maybe starting two Redskins?