Oh jeez I've fired too many types of firearms to even remember. I own four, but am saving up for a fifth. I really want an M4 style AR-15, but you can buy them in pieces and easily assemble one yourself. A bunch of different companies make the AR-15 model, and the parts are all mil-spec making them interchangeable.
So a short list of guns I can remember using: Walther P99 .40, Glock 22 .40, Glock 21 .45, Colt Python .357 Mag., Czech VZ-24 8mm Mauser, M1 Garand .30-06, Norinco UCN-1201 pump action 12 GA., Mossberg 590A 12 GA pump action, Reminton 870 12 GA. Pump action, Beretta auto-loading 20 GA., Remington 1100 Auto-Loading 12 GA., some weird bolt action shotgun, Sig P226 9mm, Some .45LC revolver, Ruger Mini-14 5.56mm, Ruger 10-22 .22, Some .45LC level action rifle, a Sierra Special .22 revolver, a Marlin bolt action .22 (first gun I ever used), some random 9mm, Mosin-Nagant 7.62x54mm, Lee Enfield .303, Springfield XD .40 compact, Springfield XD .40 full size, Springfield Pennsylvania Rifle replica black powder muzzle loader, Marlin pump action .22 rifle, Kel-Tec SU-16C 5.56mm, Beretta M-9 9mm, M-16A2 5.56mm annnd I that's what I remember.
Yes, I'm a gun nut and most of my friends are too, so I get to use a wide variety. And yes, video games are very unrealistic when it comes to the ease of handle and using a firearm. Guns are heavy, it takes a ton of practice in order to be proficiently accurate with them, and the recoil is never well portrayed.
The M-16A2 is the only fully-automatic weapon I've used (technically 3-round burst), and that was during my military service. Controlling a fully automatic firearm is difficulty x10.