best defensive caliber and why?

[popplecop]

My favorites are semi autos based on the tried and true 1911 frames, have them in 45acp and one in 9mm. The 9mm was an experiment as was never a fan of it, but learned something from it. Mine is a ParaOrd LDA Model PDA, 9 shot single stack, controls all the same as my other 1911s except a wonderful DA trigger, ambidexrous safety, night sigths, 3.5" barrel, dual safety and very accurate. All that and then the one that best fits in any sort of pocket, light, 15 yd. handgun is a Ruger LCP 380, another experiment that I really enjoy and will keep. As far as ammo goes for any of them there is all sorts of great defensive ammo available in all 3 calibers. And yes I have a number of S&W revolvers in N,K and J frames too. Flat single stack mags easier to carry than speed loaders though.