S&W 686Plus; Ruger New Model Blackhawk Convertible
As much as I like K-frames, the slickest revolver I have is my 686Plus with a 4 inch barrel. I bought it from the days before the Hillary Hole (I spit).
For single action, I like the New Model Blackhawk convertible. Mine's got the 4 5/8 inch blued barrel, and if I didn't have it, I'd buy it in stainless with 5 1/2 inches of barrel. Utterly reliable and will take loads I wouldn't put in my S&W.