The AA-12 is a bad choice: It runs through ammo like forget, and the drum mags are so big you could only carry 3 at a time. The G18 is likewise, you run through mags so fast and it is impossible to fire full-auto without tearing your arm off.
I'd go with an M-4 with a grip and a silencer, drum mags in possible.
A SIG-SAUER P226 wit ha silencer and flashlight for the large mag sizes
And the mele would probably a modded cattle prod or something like that.