I have had many high-end systems in my vehicles , and have also had many friends with them. First thing I'll mention is Alpine. Every alpine deck I have ever seen in either my own or a friends vehicle has had major problems. They are also notorious for skipping especially on burnt cds. Alpine does have good amplifiers and speakers though, I still use their DDDrive mids/tweets in my car.
Sony is in th e same boat, I'll take a Sony camera or video cam over any other brand but will never anything with the sony name in my car. From what I have seen, pure trash.
So far my preferances are Kenwood/Clarion/Panasonic decks. I had a kenwood Excelon deck in my truck(off-roader) and it still works awesome to this day on or off-road, and only skips if u have ran a cd through a meat grinder. The only reason it was replaced was to upgrade to a dvd/MP3/WMA..... deck, Kenwood also. The new Kenwood is modular, so u can add whatever u like to it, gps nav, sat radio, just about anything although a lil on the pricey side
For Speakers I have been through so many its not funny, the alpine DDDrives still pump, JbL are good but only in the high end, JL are a good all around speaker no problems and are still what runs in both my vehicles.
Amplifiers are what really makes a system. In my first system I had a 300watt amp running my bazooka tubes. They sounded good and were fairly load. One day that amp fried so I went to the store and was talked into a Rockford Fosgate 2 channel-60watt amp. I even told the salesman theres no way that amp was going to power my subs comparably to the old 300watter. Was I wrong, the 60watt RF amp was a way cleaner sound, and was actually able to push the tubes louder then the old amp because of this. This amp was also th size of 2 pieces of bread. Lesson learned, bigger numbers does not always mean better.