I discovered so much music through last.fm back in the day. There were so many obscure and weird bands to find in their «Related artists» and whole genres I feel I’d never have heard of if not for last.fm
I always felt like the Spotify recommendations were cheap knockoffs. Its clear Spotify either earns more money from those plays, or the artists have gamed the system.
Edit: by cheap knockoffs I literally mean artists who look and sound like the original. Eminem knockoffs come to mind as particularly striking.
Google Play Music was pretty good, especially the auto-generated playlists (albeit a bit repetitive after a while), made me discover a lot of artists, so of course Google had to kill it.
Nowadays I use Deezer and it's definitively worse.