My choice isn't there. I play 360, so it's the RPD. The gun rips stuff to shreds at any range. I've stopped using it now, it made me feel very dirty. M14 FTW, once you get the hang of it. Otherwise, M16/Red Dot/Double Tap or Stopping power does very well (which I now see isn't there either...) I guess I'm picking M14 then.
Reasons:
Very accurate once you ditch the crappy iron sights
Very powerful (two shot kills most of the time)
Correctly used the rate of fire is fine due to firing as fast as possible at close range, and not worrying about recoil at long range.
Only negatives for me are the crap iron sights, high recoil, and possibly to little reserve ammo. I use bandolier though, so it's not much of a problem.