Wow, where to begin? As a maker, I think Ford does it best overall.
The best factory system I ever heard was in a Lincoln Town Car… a rental! Due to flights being snarled up, I rented a Town Car and drove a few of my associates from somewhere in Connecticut to Philly at night. Papa was a Rolling Stone on the radio was he best I ever heard… and that was around year 2000. BTW, not all radio stations use compression… some actually care about sound quality.
I forget the year, but I was working out of CHicago and was renting a car every week… I tried em all! Volvos, GM, etc… all of 'em! First thing I do in a rental is turn the bass/treble/EQ etc to flat. Why EVERYONE seems to turn the bass and treble up to max is bizzare to me.
Ended up liking a Ford Thunderbird… just a solid, comfortable car… with a great stereo. Ford seems to do it better than anyone.
I have German car with a Bose label (actually a Becker system)… I can’t say it sucks, but it is not great. I have always swapped out car systems for aftermarket… NEVER had one I liked (but then I never owned a Ford product).
Bruce in Philly