I’ve been surprised by how poor Spotify’s recommendations were - they bought the Echo Nest, and seem to have people who are quite smart working on it but when I tried it after Rdio closed no matter what I started with it’d be top 40 after a couple of tracks, enough so that I wondered if there was a background deal with the record labels.

Apple Music is notably better – and has the benefit of not funneling your money to the likes of Rogan – and the recommendations will be fairly good within a genre but it does overweight your library a bit (I wish it had a “I’m looking for something new” / “familiar” toggle).

I am curious what Rdio did differently as I had a very good success rate with their suggestions and it seems unlikely that there was some secret sauce nobody else has been able to figure out.