Which do you prefer on MW2, ACR, or Scar-H?

I have been wondering this for a while since i went prestige for the 2nd time i didn't want the same nooby gun, the scar, but i still like it. Which do you prefer, and what perks and stuff do you use one it. Not using the ACR a lot is a down side since now i don't know whats good on it. Thank You to all that help!