EDIT: My favorite weapon isn't the SAW, it's the M60. Don't know what I was thinking.
Once I got the M60 I started using it exclusively and it's freaking awesome. Takes some major skill to use it though...when compared to the M4 and M16 it's REALLY inaccurate. You have to fire the gun completely different at every angle and distance. I used to have the ACOG on it but I traded it for the Grip. I also have Double Tap and Steady Aim enabled on that setup. It's pretty brutal once you get the hang of it. Got first place today on a 24 player map. It's funny to see all the grenade launcher/sniper/M16 whores and then a guy with the M60 in 1st.
Not sure if I'm gonna keep the Grip on it. I really like the ACOG and Red Dot, but man, there's nothing like having an M60 that fires at fast AND is effective at close range.