The simple answer to your quality question is It depends. Sorry, this is going to be long but, helpful I hope.
It is not only the quality (and philosophy) of the mastering as Edwin notes, but the quality of the vinyl used (percent virgin versus recycled- a particular problem with the '70s records of my youth), the variation in stampers used for an album by the various pressing companies, etc. As to new versus old production, most of the record presses used today are antiques with parts scarcity [although last week, a Canadian company just announced a completely new press, designed from scratch] and again, there is wide variation among them as to the quality of their product. I've had brand new lps which were unlistenable due to underlying noise level, while others are dead quiet like a cd. There are some reissue companies from which I would never purchase a new lp, while from others I have no hesitation. However, sensitivity to noise varies from person to person and is somewhat dependent upon your particular cartridge, stylus geometry and turntable. Then, as you correctly note, there is the whole can of worms about a pure analog information chain versus a digital fox in the hen house.
Regardless of new or old, the most important piece of equipment is a record cleaning machine, and I don't mean just a record brush. Even brand new records need cleaning before playing to eliminate the mold release and particulates from the press and packaging. With a high quality cleaner, you can get peak performance from a used record which may be the better version of the material (some reissues / remasters are subject to the loudness wars so prevalent now).
There are a variety of web sites out there which post many of the variations of these factors. I warn you from my own experience over the past several years in returning to vinyl, it can be quite the rabbit hole. Or, perhaps to use a better description from The Matrix, do you want the red pill or the blue pill?
I can email you a few of the pertinent web sites I have been using, assuming your profile is up to date. If not, contact me using mine. Happy to help.
Jon