Looking to drop a player

I’m looking to make some moves on waivers and can’t decide who to drop. So help me out footclan! Should I drop Demarco Murray, Frank Gore, or Dak Prescott in a standard league to pick up either Theo Riddick, mike Davis, Dede westbrook or Doctson? I have Alshon, Crabtree and Julio as my other receivers Burkhead, Jordan Howard, Alfred Morris and Zeke as my other RB and Rivers as my QB.

Thanks footclan!