Hollander Cooper: Any Old West guns (Call of Juarez: Bound in Blood and Red Dead Redemption)
Guns have gotten too complicated. Call of Duty's rifles have two multiple sights, grenade attachments, extended clips, and other peripherals created exclusively to allow one person to kill more people without ever looking away from his red dot. My favorite guns, though, haven't been used actively since the late 1800s, in an era that I've always considered to be the Goldilocks Zone of awesome firearms: the Old West.
Seriously, think about how interesting that time was for firearms. Muskets and the like were on the outs because they took too long to reload and were dumb, and machine guns were still some 50 years away. That's why I love the West, and think it's an awesome era for shooters to be set in. Red Dead Redemption's revolvers were fantastic, and the guns in Call of Juarez: Bound in Blood (seriously, it's not an awful game!) had an amazing, physical feel that make modern military shooters feel weak.