Depends on the characters I have. I'm a gun nut (No, not The_Gun_Nut!), so I pick and choose what I figure the characters would like the best.
In my stories, Jon "Money" Johnson carries a Browning Ultra-Power in .45 ACCP (Automatic Colt Caseless Pistol) with a screw-on adapter for a silencer, which he usually puts a flash suppressor on to protect the threads and to handle the muzzle flare from such a short-barreled, high powered pistol, and has replaced the integral laser sight with a smartlink. As well, he has a pair of Colt Cobra TZ-118 SMG in his car's door holsters, and a heavily customized AK-97 in the trunk. (He calls her "Matilda".). He also has a large collection of modern and classic firearms, such as a 165-year old Holland & Holland Royal Deluxe Double Rifle in .600 Nitro Express that he picked up in Africa on a hunting trip at his sister's request (The hunting trip, not getting the rifle.). He's very much a gun nut, as well as a fan of knives and blades, and is quite likely to pull out juts about anything you can think of. I've used him as a NPC and Mr. Johnson a few times, and the PCs have seen him go on a fishing trip, having depth charges loaded onto his ship.
My other story protagonist, Nas, carries a stock Smith and Wesson M650 Heavy Revolver in .500 S&W (Ruger Super Warhawk stats), and a pair of modified Ceska Black Scorpions in .30 Caseless Carbine. He has the revolver for intimidation purposes and as his "Driving Pistol", and the machine pistols as anti-personnel weapons. His main weapon is pure stubbornness and whatever he's currently driving, as he's a wheelman extraordinaire! He just came into some cash, so he'll be upgrading soon.
The first PC I've made that I call "The Accountant From Hell" (For a hopefully upcoming game) has a customized Colt Manhunter in 10mm Caseless that someone suggested the name of "Income Statement" for, and a heavily customized AK-97 in 7.62mm Caseless that I named "The Great Balancer (He uses it to balance the book of combat, as he lacks serious combat abilities.). He also has a full-sized 12 gauge Defiance T-250 Shotgun with Slugs and Shock Lock shells, and a stock Beretta M70 SMG in 10mm Caseless, and has a Colt Asp in .38 S&W Special with EX-Ex Rounds and some speedloaders hidden away in his bolt hole. As he's a neat freak, he typically uses dry lubricant. He's also looking at the Colt M2066 in 10mm Caseless as a possible replacement for the Manhunter if he ever loses it/has to dispose of it.