We could debate this one until the age of ray-guns dawns....but what the heck, I'll play.
Not sure if I would have the S+W, USP on the list.
Off the top of my hairy head, I would go something like this.
10-6 (Too difficult to grade precisely while I eat supper)
>Berretta M9, >Ruger Mk series of .22s (MkII is you force my hand)
> Luger P-08 >Sig 226 >Walther PPK
5. CZ-75 =I'm biased here but the fact remains that it is a damn good pistol
4. Walther P-38 =Pioneered the double action service auto.
3. Glock 17 = We can debate the innovation inside this pistol, but the fact remains that it ushered in the new age of service pistols. Love it or hate it, it's a world class handgun.
2. Browning High-Power (P-35) =fielded by more armies that any other auto-loading handgun in history.
1. Colt M1911 =While I'm not a huge fan, I gotta give props to the king.