I've only used the free version of Spotify briefly over a decade ago so can't really compare, but I've been on YT Music (originally Google Play Music) for a few

I've only used the free version of Spotify briefly over a decade ago so can't really compare, but I've been on YT Music (originally Google Play Music) for a few years and like it quite a lot. I use the recommendations and auto-playlist features quite heavily and it usually does a decent job with those.