in games, prolly the akimbo p90s from MW2. IRL the .300 remington ultramag. Huge range, and a very high knock down. There are probably less than a dozen real life rifles with better performance (Meaning it's range and power, i dont care about rate of fire irl) and it has a relatively common shell, and it could fire 30-30, 30-06, .308, and most of the other .30 caliber shells out there if it had to. It also comes with the same pump action system that is on the remington model 870 express shotguns and that is commonly believed to be the most reliable action in existance. I knew a guy who had his freeze while hunting, he used a fire to melt it, shot it till it froze and then melted it again, all day. it was like, 16 degrees farenheit. You basically can't make the 870 not fire, and the .300 ultramag has the same action.(if you go pump.)
I also love .38 revolvers, with longer than standard barrels. I am (im)patiently waiting the day i turn 21 so i can get my concealed carry permit and buy one.