Necromancy time! I knew this thread was somewhere among the ancients.
Anyway. I've tried all of the stations, and my favourite is definitely Morro Rock. Pacific Dreams is all right, too. The rest have too much music that I really dislike (rap, disco, electronic).
Morro Rock plays nothing I dislike, and lots of great songs. I particularly enjoy "So It Goes" (which started playing as I started typing this sentence...), the Samurai songs (especially "Chippin' In" and "Never Fade Away"), and "Friday Night Fire Fight" (that one's also a neat reference to Cyberpunk 2020).
It's funny, really, that I like the Samurai ones; back when "Chippin' In" and "Never Fade Away" were first released four years ago, I didn't like them as I found the vocalist was shouting rather than singing. Overall, I found the music too heavy for my taste.
Listening to Morro Rock while driving whichever car I happen to be using creates an excellent atmosphere, and I feel like I'm playing favourite racing games of mine (two Need for Speeds from the 2000s). Except, in those I tend to drive in third person, but in this game always in first person. Way more immersive; I feel like V is actually part of the city.
Makes driving super enjoyable!