I use Navidrome. Really well made clients for anything, ability to select transcoding method (or lack thereof) based on a client, changing of following songs etc.

May not be the fanciest, but I use MPD.

When I'm home, it outputs to a pipe that feeds Snapcast for my multi-room audio. If I'm away, I can stream it through MALP on Android or through a web interface (myMPD)

I use navidrome, it's pretty simple to setup and use and has support for many clients. For mobile I use Ultrasonic and sonixd for desktop

I've been using Plex and Plexamp for ages. I have about two terabytes of flacs in my NAS, and Plexamp seamlessly encodes it to 128 kbps Opus when listening on a mobile network, or streams the flac as-is if on Wi-Fi. It has a good recommendation engine and a very nice UI. Worth the money, if you ask me.

I use Plexamp

Jellyfin a million times over. It manages all your music and has get integrations and apps.

I used Jellyfin with Finamp on my phone.

I have one /media/music folder which I have connected to both Jellyfin and Gonic (Subsonic). I use Gonic because it's lighter weight than Navidrome and I don't care about a web interface.

FinAmp is the nicest iOS music client I've found, and it only works with Jellyfin. On the Mac I recently started using SuperSonic (which is simple but has been more reliable for me than sonixd) which uses Gonic.

play:Sub is the most polished iOS SubSonic client, but I find the UI fussy and hard to use one-handed. Amperfy, SubStreamer, and Soundwaves are all worth trying but each frustrating in their own way. I like Amperfy the best at the moment.

Also Jellyfin, but I use a paid app, S2 player. Been the best out of all I've tried so far. Can even aggregate with local music stored on the phone.