Honestly, the Plex app is very decent for music libraries these days. Except for oddball VA releases and obscure mixtapes I find Plex to often be terrific at library management.
Second about this. I thought Plex would be overkill at first, but Plex is fantastic for streaming personal music library over internet (especially with Plexamp). One of its best feature IMO is you can make it automatically transcode music to Opus when streaming over cellular or download them locally as-is, saving all headaches of syncing to iDevices.
I've avoided using it because of concerns about library size. I want to move off of iTunes (launch a VM just for this) but nothing else seems to really handle managing a library. Currently trying out Airsonic but it is kind of slow and I can't edit tags with it.
I run all songs / albums through MusicBrainz Picard before putting them in the music directory structure so they're fully tagged. It only misses some of the more local / esoteric stuff I've got.