G19/G23 are good. I own neither but might pick up a 23. I've already got 9mm covered with my Steyr M9. Same basic size and capacity as a G19, the difference is that the M9 has good ergonomics. I'd probably carry it more if I had a holster for it that was quicker/easier to put on. If you need something smaller than a 19/23, the G26/27 are the subcompact versions in 9mm/.40.

Since .40 is the most common caliber used by LEOs, there are many trade-in Glocks in .40. I've seen pretty good prices on used G23s and 22s with night sites. One place to look is summitgunbroker.com.

I do carry a G36, the only single-stack Glock. Conceals very well in a CTAC and I'm comfortable with 6+1 of .45. That's only one less round than a standard govt model 1911, and I can actually conceal a G36 with summer clothing.

When I just want to throw a piece in my pocket and head out the door, it's my S&W 37-2, which is one of the airweight series of 5-shot .38spl revolvers like the more common 642. Ruger SP101 would be a great choice if you wanted to carry a .357.

If you want an ultra concealable mouse-gun, Ruger LCP or Kel-tec P3AT, both .380. I'll probably pick up one or the other eventually.

Whatever you get for carry, make sure the sights are visible at night. And I won't get into caliber wars, but IMO the bare minimum-power round you should carry is .380 or .38spl.