Pandora. No ads, higher quality audio. I do it because I appreciate what I get from the site, same way I buy the Economist even though I can read its articles online for free.
Rhapsody, on the other hand, lets you play any song from their library at any time you want. You can skip, go back, scrub, and play songs/albums/artists/playlists just as if you owned the songs (you can actually even download the songs and drop them on any MP3 player if you get the mobile plan).
MAJOR difference in the service they provide.
If you pay for Pandora, you get six skips per hour per station. Free users get six skips per hour, across all stations.
I can't quantify it but Pandora does a much better job at playing music I enjoy in the context of the previous music it played and I enjoyed. There will be times when it hits streaks of an hour of non-stop amazing music song after song (with only a few that I've heard before).
Other services I've tried are not much better than a genre on shuffle.
http://www.fastcompany.com/1718527/pandora-ipo-tim-westergre...