I have both. I am an OLD revolver man, so you know my prejudice. Both are good and I have full confidence in each, at least as much confidence as I can have in an S/A handgun. No reason not to trust the Shield has presented itself over quite a few hundred rounds. Each has it's pluses and minuses. The Shield is flatter and carries a bit more ammo. Reloads are larger and easily carried and carried out. I have faith in the 9MM round for personal defense.
My favorite revolver for edc is a model 640-1, not because it will fire .357 mags but because it is stainless steel and it really works for me with the slightly longer barrel and a set of Pachs installed. I am fully comfortable with the five rounds chambered and experienced and at peace with reloading if necessary. I have full confidence in good .38 Special ammo and usually carry Speer 135 grain Gold Dots for business.
I shoot each about equally these days, given my diminishing eyesight and open sights. My personal feeling is that I have more confidence in the revolver (any of them) while still having enough confidence in the Shield to carry it without reservation. The effectiveness of either is basically dependent on my ability to deliver rounds to the most effective and incapacitating location. As far as triggers are concerned, I have fired my revolvers in the double action mode for a very great many years, and all mine have good smooth actions by design. The trigger on the Shield is more than acceptable for serious social encounters and is not difficult to get used to with acceptable pull weight as compared to the revolvers. There is a transition that must be made between the revolver and Shield triggers but that transition is not difficult for me. I practice equally with both, and at the same time.
If you must make a choice between the two, you need to make that decision for yourself after having made your own comparisons. I carry both in IWB holsters with a double thickness belt. Each carries and deploys very well and each conceals pretty much equally well. Again, you must choose what works best for you.
For me, I am comfortable trusting my life to either handgun. But my revolvers make me smile, so my preference is for the steel J Frame or sometimes a steel K frame Model 10 with a three inch barrel. It's a matter of the heart!!!!