I can tell you older S&W revolvers are better made than the new one, although I hear the newer ones are improving. It seems like better production equipment (CNC machining) helps, but cost cutting measures hurt.
What Ruger has done with the Marlin rifles is pretty amazing (enough to make me want one)
When I was young (many, many years ago) a rifle that would shoot MOA was something to hang on to, nowadays many rifles will do that, primarily due to better manufacturing techniques.
When parts can be manufactured to such close tolerances hand fitting is almost a thing of the past, other than on very high end firearms.
Manufactures today, have to split the engineering, between the engineers and the legal department lawyers. You end up with things like safeties on lever action rifles, and single action revolvers....
I don't know, I like to know an actual gun smith assembled my firearm rather than an assembly line worker.... Does that make it better? I don't know, I think it depends on the manufacturer.... Did I mention I don't know???