Linux

Aqualung—does the small set of things I need it to, and is content to operate on files and directories rather than force the creation of a "music library" that doesn't in any way match how I categorize my music (although if you actually want a music library, it can do that). Only issue is that it's still GTK2, which may become a problem within the next few years.

Desktop/Laptop: Ncmpcpp + mopidy-mpd + jellyfin-plugin

Mobile: Finamp

Homeserver: Jellyfin

With this setup I'm able to manage and play my playlists on every device.

I just use Navidrome's web client. It does everything I need. DSub on Android.

MOC

Haven't used it in a while but Amberol is simple (all I need) and gorgeous (which I care about).

Spotify-wayland on hyprland. And I also definetly dont have SpotX-bash, a great spotify adblocker installed!

Musicbee with wine! I have never been able to find something that does it all as well as musicbee, and I've tried almost every single linux music player. I have a huge music library, I add a ton of music regularly. I need auto-tagging, i need to be able to sort, filter and search, a very customizable interface, all of the mp3 tags including obscure ones, gapless playback, configurable fade-in/fade-out, etc etc. With the exception of a few little nitpicks like not integrating well with the KDE media widget, and some occasional annoyances with pipewire, everything works great.

mocp

I used to use Amarok, but now I have a subscription to Youtube Music. It gives me a lot of flexibility on running it in a browser or on Android without worrying about syncing.

On Android its NewPipe. No ads, free, I can create playlists, and I dont have to store anything local.

I'm a DeaDBeeF fan. i used it on windows and still use it on linux

Foobar2000, which is a Windows application but available as a snap using wine.

I really want to use DeaDBeeF because it is Linux native and has similar customization features (I like big album art, for example), but sadly its library management leaves a lot to be desired compared to Foobar's. I don't want to have to generate a playlist every time I want to listen to an album, nor do I want to have to clear that playlist when I'm done.

I haven't found any other player with even remotely similar customization available.

audacious, AFAIK it's the only one to support vgmstream