IMHO, with jazz you get both – good music and good sound. Like @whipsaw mentioned, Rudy Van Gelder (Blue Note) engineered tons of material from the bebop/hard bop/post-bop eras. Several other labels had good production quality as well, like Prestige, Riverside, Columbia, Verve, and Impulse. I don’t know if there was an unspoken standard or a small group traveling within that genre, but most of the stuff they produced was pretty consistently good.
Yeah rock, R&B, even blues, can be all over the place. But again, I think that was a function of engineering and where/how they were recorded. Earth, Wind and Fire’s first album sounded like it was recorded in someone’s garage. Their sound improved substantially with the move to Columbia. Chicago (CTA) put out great stuff with Columbia as well.
The other day, remembering my high school days, put on “Stand” by Sly & the Family Stone. It was pretty bad. I liked that album playing on the system I had back then. If one’s system is fairly resolving, capable of faithfully reproducing what’s been recorded, then sound quality will necessarily vary based on how well it’s been engineered. It’s the old adage “garbage in garbage out” at work.
One last thing, keeping with the central theme: is it the music or the sound? I had a plumber doing some work and I asked him “… anything or anybody you care to hear while you’re working?” He suggested Vince Gill, Randy Travis, and a couple of other country artists I can’t remember. That day – song after song - I discovered how much high quality sound comes out of Nashville. Those guys really know how to engineer great sounding music! Am I now a country music fan? Well no, all things being equal, music trumps sound. Just saying …