As my carry needs and priorities have progressed I've gone through many carry guns. I went through the "OMG I might print if I do yoga so I need the smallest pistol possible!!" phase (NAA mini revolver), I went through the "F it, my neighborhood really is as bad as Fallujah" (it's not) (G17 with G30 BUG), I'm still in my 1911 phase sometimes (It's just so skinny and comfy to shoot). and through all my phases I was always the one that my friends asked "What should I carry?" (Put the Deagle down and back away slowly). I came to the conclusion that there's not one right answer, but a whole lot of the time the answer is some kind of mid-sized 9mm.
They tend to be small enough to carry comfortably, but large enough to shoot comfortably, and well. They tend to have 15ish rounds, which with modern high quality 9mm jacketed hollow points is a significant amount of firepower, and a not insignificant jump over 8 or 9 .45's. Mag capacity has become more important in my calculus as I read of more and more group attacks. They can be used as home defense and carry if budget doesn't allow for a bunch of guns, and there is a bajillion midsized 9mm's, from quality makers, in the $500-$700 range, which I find a reasonable price for a quality firearm.
Along the way I started to collect this form factor of pistol through no real planning, just "I like this, so I'm buying it". Yesterday I ran across an HK P30 on sale for $499 NIB, so I impulsed purchased it, took it home and threw it in the "9mm" section of the safe. Then I took a closer look at that section and thought "huh, I really do like that form factor."
So, a family photo:
A keen observer will notice my preference for hammer-fired, and that one of those is more a notional firearm then actual at this point. There's also most of a P228 around here somewhere that didn't make the photo.
I have other guns that I enjoy quite a bit, but for a jack of most trades pistol your 4(ish)" barreled 9mm works very very well. They also tend to be fun and rewarding to shoot.
What say you guys? You got any "go to" form factors for pistols?
(Now I have to go look for a P320/M18. Gonna need one of those to practice on soon)