Read this: I'm a huge Ruger fan, my safe has both S&W & Ruger, but the Ruger's are on the order of 10 to 1 against the Smiths. I've been smithing on both for over 20yrs, and as an instructor, I recommend the Ruger in front of the S&W most of the time. Put your flame throwers away, I'm not hearing it... Below are all of the realities I had to learn to overcome to try to get GP's and other Ruger's up to the standards of discerning S&W fanboys.
If you compare the S&W and the GP, you're looking at a double coil spring action vs. a coil + leaf spring action. This is typically why most S&W fanboys claim the S&W can be made to have a trigger feel which can't be met by the Ruger design. Whether it is correct or not, and in my experience doing action work on both, I'm more prone to say this is less true than true. Generally, if the strut is polished and the spring burnished, the shooter will not feel stacking of the Ruger mainspring, and the stacking felt is really more of the moving parts than the springs themselves.
Another advantageous feature of the S&W design compared to the Ruger is the strain screw, which gives the shooter the ability to tune the mainspring load slightly without even disassembling the revolver. There's no parallel to be had for this feature in the Ruger design, as the only ways to manipulate the spring tension are to replace the spring or remove coils (destructive, irreversible process without replacement parts).
The sear depth and angle of the Ruger is the next "weak link" in the good trigger chain. Ruger's have an absurdly safe sear engagement depth and angle, which adds to the trigger creep, and increases the pull weight. This can only be rectified by an action job by a skilled smith.
The hammer mounted firing pin of the S&W compared to the frame mounted firing pin of the Ruger, coupled with the Ruger's transfer bar, is another design aspect where the Ruger can't be made to run as efficiently as the S&W. It simply takes more spring force to overcome all of the moving parts, all of the momentum transfers, of the Ruger design, plus the firing pin rebound spring power. This really can't be overcome, but it can be minimized, which is especially more simple these days with the rear-entry firing pin design upgrade.
The Ruger does have a bit longer geometry, which offers a bit extra leverage, but also means extra travel. In this, the Ruger has a slight advantage if the sear is modified as described above, as the longer geometry gives a smoother, lighter feel to the break, even if it might have a slightly longer perceptible creep in SA.
The Ruger also has a disadvantage in its locking bolt & trigger interaction design, which unless properly addressed by a skilled smith, requires extra trigger spring power to overcome. The S&W has a fixed tip on the trigger which trips the locking bolt to free the cylinder, then cams over the bolt again upon reset, in which case the angle is extreme, but the rebound slide spring is only fighting the locking bolt spring to reset. In the Ruger, this system is much more "squishy," as the trigger plunger (not the part most people think) is sprung against the pawl, and these parts are all free to move, and the trigger plunger has a habit of canting on its axis, which defeats the mechanical advantage. A skilled and knowledgeable smith can eliminate that deflection and tune the interaction, but out of the box, the Ruger requires greater trigger reset spring power than the S&W.
Once tuned, the difference between the two still favors the S&W, but only slightly, as the minimum weight for both has to stop long before they'd functionally fail, simply to keep the triggers safe and appropriate for field use. A guy really can make either SA trigger too light to be useful. Generally, out of the box Ruger's will have better triggers these days than non-PC S&W's, but more importantly, an appropriately reworked specimen from either brand will be leaps and bounds better than either were from factory, or with simple spring replacements.