I'd tell you who, but I've got some waiver claims in right now and don't want to tip off my league mates who are on CB.
As far as Mahomes goes, he doesn't have anyone to throw to right now, and the two high safety look that is taking over the league is absolutely flummoxing QBs that rely on improvisation and the deep ball like Mahomes or Jalen Hurts does. The way to beat it is to throw to the middle of the field. That's why traditional pocket passers are thriving right now like Darnold. I'd see if Darnold or Mayfield is available off of the waiver.