You know what? It depends. Posts above are spot on.
Used to be there were no small lightweight Rugers, S&W had that covered with their air-lites/air-weights. Rugers new LCR fills that void. Finally.
And it is kinda hard to find a good, brand new single action S&W.
Strength? Used to be, maybe still is, certain loads were A-OK in one but not the other, if that is important. Does that make one better and the other lesser? Perhaps to some.
Aesthetics are subjective, but some prefer the looks of S&Ws to Ruger.
Internal Locks? There's a subject that some will argue all day as being a deal killer. Same with politics of management (historical POV, we're all in this together nowadays or better be).
My own preference, subjective as it is, the majority of DAs I own or used to own are all S&W or old Colts. Single actions are Sturm Ruger. Curious how that turned out as it was not planned.