This is largely opinionated, but i like the Steyr TMP.
Response by Lord DooDoo: That gun is in MW2, so you couldn't have used it. I like the Silenced Mini-Uzi.
Mw2-ump 45 silencer W/ cold blooded and raffica silenced
black ops-famas or galil.
MW3 p90 suppressed or acr suppressed acog
MW3: PP90M1 suppressed, proficiency range.