The "best" headunits, amps, speakers is highly subjective.
It all breaks down to what music you listen to, e.g. there's some brands/models that are better at electronica than rock'n'roll.
I had a decent stereo in my previous daily driver (A mix of Sony headunit, Denon 4 ch amp for the Orion speakers, Hifonics monoblock for the Hifonics sub), but i have'nt bothered with installing it into my current daily driver.
It'll break down and die not too far into the future. I like hardrock, punk, metal, and some electronic music, but i'm mostly into hardrock and metal. So i would choose a stereo that favors that kind of music.
To do that, i would bring a few favorite CD's with me to car-stereoshows where vendors bring their democars so i could test-run the combinations. It's been a few years since i did that last, at that time i found that Blaupunkt's Velocity series were ok for my tastes, Planet Audio too had a few sweet amps and speakers, and some other brand i just cannot remember.
If this is way too much dedication for what's basically just a wish for some ok sound, check out product reviews. A decent car audio magazine should write what music a product is best for. At least they used to, have'nt bothered to pick up a car audio mag the last seven years. I would'nt think too much about reliabillity, most brands have their act together.
Because i love heavy guitarbased music, i would definetively check out Butler Audio:
http://www.butleraudio.com/car.php I have'nt read a current test of their products, but i once read a review where one of their amplifiers were said to perform poorly with R'n'B, techno, but it kicked ass when it played AC/DC, Guns'n'Roses, and such. I've wanted a Butler in my car since then.