Slacker
Definitely Slacker for me.... with the new ability to cache, I don't think I have any need to buy/own music anymore. I create different custom stations based on different types of music I may be in the mood for, and use my unlimited skips and ban music I don't like.... I use Slacker on the computer all day at work, Slacker on my phone at the gym or traveling and just wish I had the ability to stream music from my phone to the my car stereo via bluetooth so I could ditch Sirius