If double-action trigger pull is the way you measure your revolvers, there's none smoother than the S&W 686.
If, however, you are interested in purchasing an accurate, well built, rugged, great feeling, good looking gun that costs $400 or less, then look no further than the Ruger GP-100 in a 4" stainless fully lugged barrel. When shooting .38's, there is NO recoil. When shooting .357's, the re-coil is just enough to let you know you're shooting high performance ammo.
And, in my humble opinion, after several hundred rounds with both the S&W and the Ruger, the GP-100's single action trigger is a little crisper than the Smith. I generally shoot single action when I'm at the range, anyway, so the Ruger wins hands down in my book. And you'll save a hundred bucks...
Just my two cents...
------------------
Triggers exist to be pulled... again and again.