I have experience with the Colt 1903, the NAA Guardian, and the Keltec .32's.
For shootability, the Colt is the pick, but it is unwise to carry one cocked and locked IMO. For carryability, the P-32 wins. The Guardian is about the same volume as the P-32 but it weighs enough more than the P-32 that you can't get away with carrying it in the pocket of a pair of shorts held up by only an elastic waistband. In its defense, though, my Guardian has a better trigger and is more accurate than my p-32. My P-32 has also had reliability issues and required a trip back to Keltec.