Sound is always a personal experience! You're building your personal car audio system, not someone else's. Sound not appreciated by a friend or car audio judge is not bad sound. You have to listen to your system, choose what you think sounds best!

Generally makes that specialize in one product make better quality, so if possible choose a speakers-only make for speakers and an amplifier only make for an amplifier. Below is a list of my personal opinion on some makes. This is certainly not a complete list because it only mentions makes I tried in my own car or makes I heard so many times I feel confident judging them anyway.

You can recognize a good car audio shop by their interest in you. A sales person should ask about your car, your favorite kind of music, your budget and your current system. A shop that says "this is the best ..." without informing about your wishes, means "I make most profit on ...". There's always the best solution for your specific situation, not one that suits all. Find a shop that advices based on your situation, they may be more expensive but with a better result it is worth it.

While listening to equipment in a store keep in mind that it will sound differently in your car. Enclosures determine most of a speaker's sound and you won't install your car speakers in a demo wall in a room. Subwoofers totally depend on the enclosure, full range speakers will sound more like in the store and tweeters are only affected by the angle of installation. Use the demo in a store to get a general idea of the basic characteristics of a system, don't expect the same result. You may well get a better result because your car is smaller than the shop making it easier to fill with sound.