For out of the box smoothness, I'd have to say, as a brand, S&W takes it.The old blued guns seems to have better triggers, but then again, they've been used. I've never handled a Colt DA revolver, so I can't say.
Now, just about any DA revolver can be tuned to have a great trigger. My Rugers are smooth as glass, although still heavy (which is the way I wanted it, just did a nice deburr/polish job). But out of the box, S&W is tops.