I've carried a bunch of different guns over the past couple of years and my favorite continues to be my Star Firestar Plus.
The Stars are no longer imported into the US, and parts may become a problem, but they are all quality guns.
The Star Firestar Plus is an alloy-framed, steel slided double-stack. single action in 9mm. WIth the right mags, it will hold up to 13 rounds +1 in the pipe.
Its not much larger than a Kel-Tec P-11, smaller than a SIG P-239, holds more rounds than the P-239, and easier to shoot than most of the smaller guns.
I had frequently carried a Kel-Tec P-11, but in several different IDPA matches and practice sessions, found I couldn't hit the broad side of the barn with it -- under pressure. (It was pretty accurate when I was relaxed, and punching paper. But that's not the way you learn to protect yourself.) That is NOT the case with the Firestar Plus; in fact, I won one of our small local matches with it, shooting against a number of expensive guns, including a couple of Wilson customs.
The best part of this story is that I picked mine up in a pawnshop for $129. But I'm sure more can be found in the $200-$300 range. (I traded the P-11 for an old, but very accurate .22 rifle set up for NRA. Great gun.)
Good triggers, light, compact, accurate. You could do worse.