I've been a Plex user for years. I started playing around with Jellyfin this week and I think I'll probably use both for a while since they can share the same library.

Plexamp has been great for music. I can put on any CD I own, in FLAC quality, without having to go locate the physical disc. I've spent much of pandemic filing in holes in the back catalog of my favorite artists.

If I want a mix, I tend to open up Tidal and let it build a "radio station" based on my mood.

Also a plex user for music and have also played with Jellyfin. My impression is that in a couple years Jellyfin will be the go to but that it isn't quite up to snuff with Plex yet (especially wrt music) though some projects like JellyAmp are changing that.