As for Youtube music, yup, that's undeniably a good deal. The music services should watch out, especially in younger demographics (I'm already 30+, Spotify premium user since 2009). Apple will probably push Music even harder and bundle that with their new video streaming. Spotify's really trying to become the defacto podcast service, which sucks in its own right (unlike Apple Podcasts, no user facing RSS support for indie premium content etc. Podcasting is the last free rich medium on the internet, largely thanks to Apple).
As for music, I'm too deep in the Spotify ecosystem myself, with stuff like proper Last.fm integration, recommendations and consistent audio quality.
I can't really enjoy music with that mushy sound typical for content that has been lossy-lossy transcoded tons of times. Of course, I have to deal with that for all the awesome live takes[1] available on Youtube, and there I'm of course just grateful they exist.
Spotify's audio didn't use to be all that great, except with the normalization turned off. Now with their 'quiet' normalization option, that doesn't compress quiet tracks (a clear edge over Apple Music), it's starting to sound transparent to me, as -q 9 encoded (~320 kbps) Vorbis should.
Youtube doesn't allow disabling of normalization at all, and it's not super clear to me when tracks are clean encodes sourced from the proper music distribution ecosystem that stocks Spotify, Apple Music, Tidal et al.