Selfhosted

I highly recommend a Navidrome/Slskd/beets[lyrics]/Symfonium setup!

I have a Proxmox container running: Navidrome, that serves music in a Library Folder (B); Slskd, that serves a SoulseekQT web UI and downloads to a Download Folder (A); and beetbox beets program with the lyrics plugin installed via pipx that has config parameters set so that I can manually run it, it'll detect and allow me to identify songs downloaded to Folder A, inject synced lyrics, and move them to an organised folder structure in Folder B.

• Navidrome doesn't need organisation, I just do it to be neat.
• beets uses MusicBrainz and another I believe for song/album ID, and lrclib for synced lyrics
• I also have Lidarr set up to download from Soulseek with the Tubifarry plugin, get lyrics via lrclib and move to Folder B with the same structure as beets, but its metadata is heavily lacking and many images and artist song data is just nonexistent after about two months of "populating" (see below), so I recommend keeping the manual Soulseek/beets approach
• Again I recommend ignoring Lidarr or maybe using it for a visual library without downloading, but there is a pro, now I've configured it - Lidarr doesn't often automatically request and then organise music, but when it does, the music is exactly the quality I requested. So at least Tubifarry is solid.
• You can use any Subsonic client but I find Symfonium to be incredible. Paying these devs is worth it!
• slskd can be configured to run beets after download I believe, but I haven't figured that out and don't plan to, for want of less complexity.

I'm surprised to not see this suggestion, but Plex does music pretty well and they have an app dedicated for music/audio called "Plexamp". Though I don't think this app is on things like AppleTV/Roku(haven't looked).

It's so-so when it comes to playlist building...but the app on mobile works and I use it for audiobooks mainly, but I am starting to plan to use it switch off Spotify here soon.

My current setup, is as follows:

Personally curated music I buy and organize using Picard into folder A.

Lidarr is configured with folder C, which is a mergerfs volume consisting of folder A and B. Folder A is read-only, and any writes on C go into folder B. This way Lidarr can "see" all my existing music, while any automated downloads go into folder B, keeping them separate from my organized files.

Lidarr actually works, because it is hooked up to Soulseek using Tubifarry with ytdl as a fallback. I also have an import list hooked up to my last.fm recommendations to automatically download new stuff I might like.

When I feel like it, I go through folder B using Picard, moving things I want to keep into folder A.

To access my music, I use Jellyfin, also through folder C. My clients are Feishin and Symfonium.

In Symfonium, I use smart playlists for discovery. These playlists populate based on stuff like "unlistened tracks" or "multiple plays without being favorited" and "recently added from favorited artists".

My favorite feature however is the tag-based endless playback which allows me to pick a track to start with, and then swipe through music with at least some kind of logic to the progression. This is my main way to browse my library.

It works extremely well, with the exception of files that don't contain many tags. Hence my main pursuit has been to find a good way too add at least some genre tags to ALL my files. I haven't found a final solution.

For iOS support, look at Navidrome for the server and maybe SubStreamer for the client.

Well, there is Mixarr. I believe it downloads and gives recommends. However, there is also a version if you just want recommendations: Mixarr Unleaded which the dev graciously modified just for me apparently. Thanks aquantumofdonuts!! So I feel obligated to recommend the unleaded version of Mixarr.

I decided to go bare minimum effort to get the self-hosted music expirience, so I'm just hosting the music on NextCloud for the Symfonium app to grab. I downloaded most of the music from YT music using yt-dlp, since that's what I'm quite familiar with and I don't have the arr stack set up yet.

I'm planning to move to Navidrome or Jellyfin soon™

Happy to hear great suggestions in other comments

I too want the features you list, not sure how doable the recommendations would be on a local server for songs that are not on there already?