Hello,I'm a fan of realistic guns in the real world.Although I'm not good at knowledgeable in the guns as some other users of this site are,but I'll do my best.
There is a list of the weapons what I like
M16A2 with M203 40mm grenade launcher.
Colt M4A1 SOPMOD with Aimpoint CompM2 reflex optic, KAC RAS railed handguard and vertical forward grip - 5.56x45mm
Mk 18 Mod 0 with LMT rear sight, Crane stock, and RIS foregrip - 5.56x45mm
M60 machine gun - 7.62x51mm NATO
M14 with scope - 7.62x51mm NATO
SIG-Sauer P226 Navy, this version used by the Navy SEALs - 9x19mm
Heckler & Koch MP5A2 with Surefire 628 dedicated forend weaponlight - 9x19mm
MAC-10 submachine gun with Sionics Two-Stage Sound Suppressor - .45 ACP
Heckler & Koch Mark 23 with KAC suppressor - .45 ACP
Sa Vz. 61 Skorpion - .32 ACP
Norinco Type 56 - 7.62x39mm.
Mossberg 500 with heat shield - 12 gauge
Remington RSASS - 7.62x51mm NATO
M40 sniper rifle - 7.62x51mm NATO
Glock 18C (3rd Generation) - 9x19mm
Steyr AUG A1 - Mitinary Version - 5.56x45mm