I have always spent my money on equipment not stereos for either the car or home. That being said, my dad had an 87 Ford Taurus company car with JBL factory speakers that sounded exactly like the my ruff mixes sounded from the studio control room and I mean exactly. I have never heard any other system that could do that, it was weird.
The stock one in my ‘18 Subaru Legacy was quite good.
The one in my ‘13 Hyundai Sonata is decent, there’s an odd midrange that can’t quite be dialed out. But overall it’s decent.
I haven’t replaced a stock stereo in a car since my high school days. Most modern cars I’ve owned had decent enough stereos. I want to feel immersed in sound, but I’m not trying to wake up every neighborhood with crushing volume and bass. Though I would be interested to hear the detail in a really high end system.
I recently upgraded my 2007 Silverado with a Kenwood unit with Android Auto that mirrors my phone navigation, all new Kicker speakers, and a backup camera. I was going to add a small subwoofer amp, but decided it wasn't necessary once I eq'd it to my liking.
Good ones? Nothing fancy...pretty much use OEM until they die, then replace with something fairly generic.
My first 8 track deck in the early '70s was a Motorola that had a rollup faux wood front (like a roll top desk)...pushed all the way down, it ejected the tape...it could be pulled all the way up to hide the tape and player front. That was pretty cool. I searched, but couldn't find a photo. That one actually survived a theft attempt at an open venue concert. I got back to the car as the thieves were leaving...heard them dump it as they ran, and found it in a car with open windows parked a couple of slots down. I collected it and my tapes, and left out of there like Mario Andretti (Charlie Daniels ref intended).
I have a Clarion stereo cassette player that I bought in 1983 for my brand new Ford Ranger. Still works, and is now in my 2002 Chevy Express van. Last week the volume knob broke off, but it still works fine. (sorta).
This is indeed a good thing for nostalgia...times and technology have marched on and it's a whole lot more difficult to put an aftermarket head unit in many current vehicles because of how much of the rest of the vehicle electronics and controls are integrated into the OEM head units. A lot of aftermarket action now is around speakers and amps because of that, rather than head units.
The only vehicle I did anything aftermarket with that I can remember was my very first one...a 1969 Dodge Dart that only had and AM radio in it when I got it for my 21st birthday. I believe I slipped a Clarion AM/FM radio in it's place and also put a separate cassette deck in. Since both were independent, I made up a switch of some sort to control which was connected to the two 6x9 speakers I put in the back. I don't remember if there were any speakers up front...too long ago!
My favorite car sound system is the quietest car interior. That road noise destroys the best stereo system. So it's probably a Lincoln or a Caddy or something like that. Look who sits in there with the expensive ones!