I’m incredibly impressed by the new Rdio design, and think it is far more usable, intuitive, and elegant than Spotify. While the redesign was introduced at SXSW, it just went live for all users.
I don’t currently use any streaming music service, since my collection is a bit too obscure to get full coverage (Rdio only gets ~60%). However, if I was to take the plunge, I’d definitely go with Rdio.