Vice City has the best soundtrack, followed by San Andreas. I really like 80's music. I don't like modern music too much, so I didn't really like GTA 4 and 5 soundtracks.
I really like the GTA Vice City Soundtrack, because those were some good songs and years - some of the songs include, Listen to your Heart by Roxette(1988), Don't Speak by No Doubt(1995), Owner of a Lonely Heart by Yes(1983), Who Killed the Radio Star by The Buggles(1980), and Self Control by Laura Branigan(1984).