I'm not sure I could pick a favorite, especially since I have a couple I've yet to shoot. One of those is a Ruger Mk-II Target, but I expect it will be as boringly reliable and accurate as the Mk-II Standard I have shot.
I have an FEG AP-22 (Interarms version, not SMC) that is downright handsome. It's a rimfire version of their PA-63, and I find it slick and solid-feeling in hand. The DA trigger is all-but unusable, but the thing is pretty accurate. It's only for HV ammunition, and that's stamped on the mags.
I have a beautiful Smith and Wesson 63-3, bought a year or so ago, but haven't gotten around to shooting it. My guess is it might be "the one" for this thread subject if I do.
I really like both my Heritage Rough Rider revolvers, one of which is a "birdshead" 3.5" model. They're hard for me to put down once in hand. But, I also have a Ruger NM Single Six among those guns I have yet to shoot.
For now, I guess the Interarms FEG. But that might change when I fire the 63-3...