Pandora or Spotify , as for me, I will choose Spotify. Why? First of all, Spotify allows users to access its music library for free also. Besides, it offers a big music library that I can find all favorite music and playlists.
Besides, I have a powerful Spotify Playlist Converter that can help me download and convert Spotify files to all kinds of audio formats, like MP3, lossless FLAC, etc. In this case, I can listen to Spotify music on all devices with ease. So why not Spotify rather than Pandora.