it's closed source, but Roon is pretty darn good. Slick UI, tagging, artist/album information, local/remote playback, speaker streaming. I have it pointed to an NFS share on my file server. It handles large (250k+ songs) libraries reasonably well. They integrate directly with a couple services, though I've never used them.
the selling point for me, over other music servers(I've tried almost every one mentioned in this thread), was that it was a much better ux than any other offering. for the most part it has held up or exceeded recent comparisons.
disclaimers: it is not free. some might say expensive.
as seems the norm these days, the forums have some admin moderation problems.
they've not historically listened to user feedback seriously, though that has changed drastically over the past year.
they just got acquired by HK... which could really go either way long-term.
NGL, it took many years for it to mature to this point and it continues to be bumpy; though nothing worse than open software I've used and it is nothing if not reliable.