Alpine high end stuff is nice, the low end stuff is ****. Same with almost all car audio equipment I suppose............
Clarion Audio has some really nice decks in my opinion. My first choice on decks.
Alpine and Kenwood both have some really nice decks also. But there are so many to choose from make sure you pay attention and dont buy the bottom line crap...........
Pioneer Decks are nice if your going to really be "pumping" your music as the mosfet internal amp does not overheat as quick.
Sony makes loud equipment but the sound quality lacks.........Kicker speaker are the same. Very loud, not very good sounding.
JL Audio (if you can find any local) is GREAT all the way around. They have AWESOME STUFF!