I second going to crutchfield.com. Good comparisons, and install info, plus a decent overview of what is new and hot.
From what I’ve seen, there are three basic types of people that go into high performance car audio shops.
Type one is the “competitor” he knows the limits of the gears he wants, and knows what components go best with each other. Money is not really an option for him, as he plans on winning a lot of it back in competition purses.
Type two is the learned audiophile. They have done their research, have a specific grouping of components in mind, and often have to special order the parts they want. Price is the cost of doing business for this guy. He won’t win any “loudest stereo” competitions, but he’s confident that his system is the best. For the most part, he probably makes a good argument for that.
Type three is the “Make me a kick-ass system for my car. Here’s how much I have to spend.” Will you get a great system? More than likely. Will all of your components be the best available? Of course not. Sales people at car audio places like to make money. They like to sell great gear too, but if you’re on the fence between two types of product, they will most likely tilt you towards the one that makes them the most money. After all, you may not be able to tell the difference anyways.
Name any brand of speaker, amp, deck, crossover, wiring system, cabinet, etc. ,and you can find people that claim that it is the best “thing” of its kind in the world. That’s not false, and it’s not true, it’s just hype. Negative feedback is not nearly as prevalent as praise is, so the field is not as level as one might like it to be.
I can tell you how much I loved my Sony deck, my RockFos tweets, Infinity mids and Kicker 12" in the trunk, but it may not be the best system for you.
Anyone who answers your OP with a definitive answer, is either trying to sell you something, or is just enamored with a brand.
The best and only answer is to shop around, do some research, ask a lot of questions, and make an informed decision. Hopefully you can talk face to face with a professional that can clarify the specs of various components, and help guide you towards what’s best for you.
Also, get a really good security system FIRST! A kick-ass sound system means nothing if it’s stolen right after you get it. I had my deck, speakers and cabinet stolen one Sunday morning. I thought it was funny that they left the amp, and my pair of expensive sunglasses there. They came back the next Sunday and got the rest. No alarm. I’m still kicking myself about that.