My favorite weapons
Pistol
Heckler & Koch MK23 SOCOM - .45ACP
CZ 75 SP-01 PHANTOM - 9x19mm
FN Five-seveN USG - 5.7x28mm
Shotgun
SWD/Cobray Street Sweeper with short barrel and top folding stock - 12 gauge
Sub-machine gun
Heckler & Koch MP5-N - 9x19mm
Heckler & Koch MP5SD6 - 9x19mm
Heckler & Koch UMP45 - .45ACP
Brügger & Thomet MP9 - 9x19mm
Assault Rifle
Colt M16A2 - 5.56x45 NATO
Colt MK18 MOD0 - 5.56x45mm
Heckler & Koch G36C - 5.56x45mm
IMI Tavor TAR-21 - 5.56x45mm
Norinco Type 56-1 - 7.62x39mm
Izhmash AN-94 - 5.45x39mm
CSA SA vz. 58 Compact - 5.56x45mm
Battle Rifle
Heckler & Koch G3A3 - 7.62x51mm NATO
Sniper Rifle
Remington M40 - 7.62x51mm NATO
Heckler & Koch PSG-1 - 7.62x51mm NATO
KAC MK11 MOD0 - 7.62x51mm NATO
Heckler & Koch MSG90A1 - 7.62x51mm NATO
McMillan TAC-50 - .50 BMG
Machine Gun
Saco M60 - 7.62x51mm NATO
FN M249E1 - 5.56x45mm NATO
Launcher
Colt M16A2 with M203 grenade launcher - 40x46mm
Next Generation Weapon
Heckler & Koch XM29 OICW - 5.56x45mm NATO 20x28mm
Fictional Weapon
SC-20K (build from FN F2000) - 5.56x45mm NATO 40x46mm
Guns that I think add and fitted in games
Just my personal opinion(just single player mode):
SOF II:
VZ58V,M16A2,PKM,M72 LAW,AK-103,P226,M40A1,Glock 17,MP5K,VZ61,M21,AUG,M82A1