Colt Revolvers are finely made guns and their fit and finish is usually far superior to S&W's Revolvers. That said, I MUCH PREFER S&W Revolvers (at least the older vintage examples made prior to 1994) to the Colt counterparts because they are just so much more robust and are better designed Revolvers, IMHO.
I have had just about every Colt model apart on my bench and somewhat dislike their over complicated and more fragile lock-work. Yes, the do work, but NOT as reliably or as forgivingly as the S&W's do. Even the coveted and sought after Python is a bit too fragile inside for my liking. If you have ever taken one completely apart you will know what I mean.
Smith and Wesson's lock work is pretty much the same for all their Revolvers but the Colts do vary somewhat from model to model. Smiths are also much easier to work on, tune and repair. The other problem with the Colts is that they have not been made in many years and parts are getting harder and more expensive to get. If you are just a collector and intend on firing the Colts sparingly I doubt you will have any major problems as they are extremely well made Revolvers - but if you want a Revolver to shoot constantly, pound the heck out of, then get the S&W without a second thought! The M586 & M686 (blue and SS respectively) are very strong, robust and popular Revolvers that should last you a lifetime. Parts are still readily available (even for the older versions) and since they share common grips with K Frames there are many many grip variations for you to choose from. I am NOT a fan of most Colt grip frames and find Smiths to be much more ergonomic. If for some reason all S&W Revolvers went away and disappeared tomorrow, Colt would be my alternative go-to Revolver (way before I'd ever consider a Ruger). I much prefer the M586 over the M686 because I just prefer Blued guns - but that's up to you of course.
PS: I do own Colt Revolvers but mostly because I appreciate how precisely they have been manufactured, their fit and their beautiful finish. To me, Colts Royal Bluing is second to none and only wish Smith blued guns like Colt. When I reach for a Revolver for shooting all day at the Range 9 out of 10 times it's a Smith. Colts REALLY SHINE when it comes to their Single Action Army's, 1911's 1903's and 1908's. Their recent offering of their .380 Mustang Auto has also been beautifully done and so that it my opinion for what it is worth............