This is a loaded question, because we've all had experiences with different brands. I'm sure if you asked around, you'd find someone who likes Audiobahn! It won't be me, though.
Bottom line:
Every major and minor brand has its ups and downs, and some brands are more consistent then others. For instance, I love my setup and its more rare parts, but I'm sure I could do better. I am certain, however, that slapping all JL Audio or all Memphis audio stuff in place of my mix-and-match setup would result in disappointment. In all, equipment doesn't matter nearly as much as install and tuning.
But, I'll play the game with you, just 'cause!
Amps: JL Audio slash series, Memphis maybe, Diamond, MB Quart's new ones, PG's Radial Sd (ugly but powerful), Alpine higher end PDX amps, Boston Acoustics amps, MTX Audio's upper end, Eclipse, Polk, JBL Power, Pioneer Premier PRS amps (the ICEpower ones), Blaupunkt PCA's (when you want to go cheap), and US Amps. With amps, its less about watts then you think! Its a lot more about flexibility, durability, and size/weight.
Coaxials: I'm not even going to answer this, because its retarded. Bluntly put, coaxials in a performance car audio system simply do not belong. Rear speakers do not belong. Go component in the front (or separates) or go home.
Components (or separates, the TRUE path): If you simply want the very best out there for mid-bass/midrange, and highend, go with separates like SEAS, Scanspeak, Vifa, etc. This takes a lot more trial and error, and you're going to need an active crossover that can do it right, but it is really the best way. If you don't want to touch this side of things, then go with Pioneer Premier TS-C720 components. Also the Type-X Alpines, JL Audio upper end (though not the top of the line), Eclipse upper end, Diamond mid to upper end, RE Audio components, Kicker SS only, Polk Signature SR, High-end JBL, and Boston Acoustics are all good. In our car, you need to run two sets of speaker wire to the doors through Molex connectors. Good luck on that.
Subs: I'm tired of hearing the same B.S. all the time about how one brand "hits harder" or "has more bump" then another. I've owned a lot of the brands, and I can tell you that the brand doesn't matter near as much as the install and tune. Use a box modeling program like WinISD pro (a freebie) and figure it out yourself, and build a box properly. Most prebuilt boxes leak air, and won't sound too hot. Another problem is that people sometimes stuff a sub into a random box and hope for the best. IMO, this is exactly what is wrong with the car audio industry. The box matters as much IF NOT MORE then the sub itself. Want brands anyway? JL is good, RE Audio is as well. As is Fi Car Audio, Eclipse, Diamond, Memphis, Boston, etc. Pretty much its all the same these days.
All the rest: What is the best wire? the best sound dampener? the best processor? etc. I don't have all the answers for you, but I can tell you some quick things to know...if you don't have all basics down in car audio but you want to, go to
www.bcae1.com and learn firsthand all about it. From there, I'll make the suggestion to not make buying decisions based on what Best Buy or CC carries in stock. Next, I recommend you do your own research on what works best for you, and not get sucked in by hype and marketing. For sound dampening materials, look up
www.raamaudio.com, and peek around. For wire, look up
www.knukonceptz.com as an idea, and for processors and such, research pays off. You can always ask me a question if you need specific help. I'm all about getting excellent sound out of cars.
