I have been totally blown away by Gooveshark. Being a browser based app It´s not as solid as Spotify, but it has no ads (for now) and doesn´t even need registration (for now). The catalog is interestingly different. It features people like Frank Zappa, Silvio Rodríguez or Ani Difranco, who are totally missing from Spotify.
Web based, Grooveshark:
Desktop App, Sportify:
Search item: Hatikvah, the National Anthem of Israel:
I got an email on November 2020 pointing me to the story of the site: