If you are talking America's pistol, the 1911 hands down. If you want America's Revolver, then it would be a toss up between 3 old timers.
1. Colt Single Action Army (Peacemaker)
2. Colt Oficial Police (and other variants including the Police Positive Special)
3. S&W Military & Police(including all the model 10 variants)
I Know others will have differing opinions and that is fine. For a wheel gun the Colt SAA or a good 38 Special is about as basic as it gets. At least for me they are.