Chris Thompson or Cory Clement or Jalen Richard

Hey everyone,
Im in a 12 person 0.5 PPT league and wanted to see who the better running back out of the following would be: Chris Thompson, Cory Clement or Jalen Richard. I current have Cory Clement and an open roster spot. I was not sure if I should drop Clement for Thompson or Richard and use the open roster spot for the other. Any help would be appreciated. Thanks!