Spotify
Currently I use Spotify and don't see too much of a need for change. The advantange of using spotify is the many social elements surrounding it, such as community generated play-lists and user taste/artist similarity. I do miss owning my own CD's though, and Spotify doesn't stream beyond 160kbps for mobile devices, allowing 360kbps only for your wall computer. This could be pretty good for competition though, especially if it supports lossless formats such as flac.