I love my P-64 for it's slimness, ability to disappear under a T shirt with shorts, excellent accuracy and never failing reliability. And I loved my PA-63 for it's slimness, ability to disapear, it's light weight and it's realibility. BUT, that all being said my very favorite 9x18 pistol is my CZ-83. 14 rounds on tap, a great trigger and accuracy and the grip has that "just right" feel and the grip and weight eat up recoil yet it is not so heavy that it is uncomfortable to carry for a long day.
I understand there will be many other answers and I am looking forward to hearing them all. Cmon guys, cough it up.
