g18 sick auto pistol. but m16 is better then the ak47. m14 is a sick looking once practical gun that is great for ceremonies now. so m14 is colliest. springlfield rifle is clasic.
In real life i would probably say the m16 or the m4, i know both are horribly out of date, but they are rather easy to shoot (I've shot then before)and don't have tons of kickback. the m4 as apposed to the m16
The m4 does the same things, accept it is smaller so you get better control.
In video games though i am going to have to say the gravity gun. hopefully the picture link doesn't fail and you can see it, it basically lets you pick inanimate objects up and turn them into lethal weapons. you have no idea how many zombies i have killed with soda can using this.