Regarding the G11, The Fallout 2 designers probably did their shopping from a book I've got called "The World's Great Small Arms", because it mentions a whole pile of weapons found in the game. The G11, the Light Support Weapon, the M60, the Desert Eagle, The Thompson, the M3A1 'Grease Gun', The H&K CAWS (Close Assault Weapons System) and the Pancor Jackhammer (Which, surprisingly, is a real gun!) For those of you, who, like me, are Bozar fans, I hate to dissapoint, but neither the above volume, nor its companion, "The World's Great Machine Guns", have anything at all that looks like a Bozar. Both volumes, of course, discuss common arms like the FN FAL, etc.
Anyway, my personal favorites are as follows...
FO1: Turbo Plasma Rifle, Alien Blaster
FO2: Pancor Jackhammer, Bozar, or anything else big an ammo-hungry.
In both games I liked using the 9mm Mauser, it's a shame you never got it early in FO2 as it was worlds better than the crappy 10mm pistol. Much rather do one point less damage on average in exchange for 20% more accuracy, which would help a lot in the early game, and 1ap faster shooting. Basically mean some characters would be able to shoot twice instead of once.