I own a LOT of both brands, but I have kind of gotten away from S&W and turned my totally on Ruger recently.
Rugers have investment cast frames and other parts like hammers, triggers etc. Ruger has been doing it this way since the 1950's, and it's clearly a proven process.
S&W uses MIM in their recent revolvers, say from the late 90's or so, when MIM started appearing in the revolvers. Ruger has also started using MIM in parts like SP101 triggers, and I think we'll see more MIM in Ruger guns. There is not a thing wrong with MIM, I own plenty of MIM S&W's and they are fine guns. Just not as tough as Ruger.
Rugers have no sideplates, like a S&W.
Bill Ruger designed the Security Six to directly compete with the S&W line of K-frame .357's. The Security Six was cheaper, tougher and lasted longer than the S&W's. So..........S&W developed the L-frame, to which Ruger responded about 4 years later with the GP100. A GP100 will eat a S&W 586 for breakfast when it comes to durability and strength.
I have no issues with the triggers of any of my Ruger revolvers. Some are slicker than others, but the same is true of my S&W"s. I have S&W's with horrible DA pulls too. Ruger DA revolvers were designed as LE duty guns and civilian defense and sporting revolvers with a low price point. They aren't out of the box match guns.
A new GP100 will run you about $550, the S&W "equivalent" the 686, will run you $650-700 or so. IMO the GP100 is much superior in all categories. A new Redhawk is about $700, and a new S&W 629 is maybe $800 or so. The Redhawk is still THE toughest .44 Magnum DA out there, along with the Super Redhawk.
Overall, S&W is perfect if all you plan to shoot are "specials"...........S&W excells at making .38 Special and .44 Special revolvers, in this capacity they will last forever. The S&W Model 10 is one of my favorite handguns, and I'm sure all of mine will outlast me.
Ruger is THE choice, hands down, for anything Magnum. The Redhawk has been proven to outlast the S&W 29 and 629, and there's a reason handload manuals have "Ruger only" loads. S&W's are simply not as strong as Rugers, or as durable.
The truth is, most people who buy S&W revolvers don't run super hot lrounds through them, or put enough rounds through them to worry about durability. So, for the vast majority of gun buyers there is no real difference to worry about other than price. The guy who buys a 4" 686 and shoots a few boxes of .38 through it a month isn't going to wear it out.
Ruger revolvers are for people who plan to run 10's of thousands of hot Magnums through the gun, this is where they shine.