Yer leaving out rimfires. Most iconic would be a Colt woodsman, Smith 22 revolver, or the far more affordable Ruger standard or single six. That said, I don't shoot 22's very often, much preferring centerfires with my home cast bullets. My centerfire pistol vote, add in order
peacemaker or clone
Luger or broomhandle, I'd accept a P38 to represent the 9mm
Then we can get to work on long guns.