I used to do SPL and sound quality stereo competitions back in the Late 90's and early 2000's. Both my brother (who also competed) and I were invited to Nationals but never went due to expense. I've got a couple of huge trophies but they didn't give out any good cash unfortunately......
Anyway, at that time it was Clarion, Eclipse, Audiocontrol and Soundstream that were at the top of the heap and I wasted a whole lot of money on all four. Everything has changed as it does with electronics and I don't know my butt from a hole in the ground when it comes to the brands anymore. I can still tell what sounds good though. My ears still work.....LOL
My 4, 12" sub setup that won me a triple points competition is now in my living room as my home theater sub and my Soundstream 10.2 is down in the shop. I went to get my purple Clarion 6.5 components out the other day to test fit them in my Camaro and the cones have become brittle and cracked...really sucks since I loved those speakers. I even called Clarion about re-coning them but it seems it's not worth it. I've still got 20ft of 1ga wire laying about too.
I'm pretty sure some things still hold true. Get the best component speakers you can afford and a really nice crossover to get the right frequencies going to the right places. Don't skimp on Amplifiers either and check their RMS ratings, not peak. If you want to save some money you can go for a slightly cheaper head unit and sub woofers. Don't by junky ones or anything but a good x-over will hide head unit flaws by cleaning and boosting the signal and box design has more to do with sub sound than anything else unless you are running them to the limit. Back in the day, my philosophy was to buy cheap subs but the best amplifier I could find and beat the living crap out of them.