Smith & Wesson 686 with a 6" barrell. My ex-wife made me sell it when my son was born. It's the only gun I have ever sold and in looking back I should have kicked her to the curb instead of selling the gun.
Today I have many handguns but not a 686. I think it will be my next purchase.
First and only (for the moment), S&W Sigma 9. I know lots of people on here have said bad things about them. Though I haven't shot it as much as I would like (and probably should), I like it overall. However, I use it mostly for my home protection weapon, as I don't like the weight of it on my belt to carry. Looking at a much smaller, lighter gun for my next to be able to carry it comfortably.
My first was a Colt Python 357 with 4 inch barrel. That thing was the most accurate handgun I have owned. I gave it to my cousin 25 years ago, and he still owns it. So I still get to shoot it every now and then.