Alpine Type R's.
I like them. They get pretty loud and have good mid range kick. The tweeters can be a little harsh at times.
My Wifes car:
Polk DB6501. They are softer than my Alpines especially in the highs. I probably have them a little underpowered though so they could possibly be better.
Both are miles ahead of the stock 6 speakers stereo. Both have a ton of sound deadening.