wow… well I’ve been outta the car audio for a couple years due to funding, but from my personal experiences…
Sony - used to be good, back in the late 90’s, once they went from high-end stuff their enitre car audio line went to hell, can’t recommend them at all unless you’re talking old-school equipment (But their stuff lasts, the HU that I bough in '97 is still working wonderfully in my brothers summer truck)
Pioneer - only used a long time ago and ALWAYS had problems with quality, astetics, and things breaking…
Alpine - Always made a good solid product, and always worked wonderfully; still running one in my DD. The only issues I’ve ever had is with the writing wearing off some of the buttons from usage, but that’s typical with anything
Eclipse- Used to be top-of-the line, hearing other things lately
Nag - Was always a great less-known-brand with high-end audiophile reviews
JVC - Was not impressed with the Kamelion that a friend had that I installed, always stuck, and just seemed to have blah quality.
panasonic - I believe they are making Alpine now, with Pioneer being the “lower” name; always had decent results and liked their units, even the lower-end ones.
Personally as of now, I’m not really sure what I’d want; hell, I would probably look for a used but good condition Alping 7949 (I beleive this was the model number); this was one of the best car audio head units ever produced as reviewd by almost anyone