In your opinion, what's the best gun (multi) in CoD 4,5 and 6?

mw2- scar h w/ bling (heartbeat and extended mags but if u dont have them use fmj or grenade launcher dont use red dot) 2ndary weapon TMP fmj and silencer or m93 raffica akimbo with silencer. I use this cl almost always and i got to a 1.12 kill/death ratio. Hope it helps.