Kid3 has been my go-to for a long time, but lately I've been using Strawberry[1] as my all-in-one music player, organizer, and tagger.
It has a built-in tag editor with MusicBrainz support and will auto-organize files. My only complaint with that is that it leaves behind old folders and files. e.g. If I have a few directories of MP3/Flac/whatever downloads with cover scans, it'll happily use the tags to organize the way I like it* but if there are "extra" files they stay put and have to be cleaned up manually.
But it's really a proper Swiss Army Chainsaw for doing everything in one application.
* Proper directory structure is "Artist/(YYYY) Album Name/NN-Song Title.[mp3|aac|flac]"
It has a built-in tag editor with MusicBrainz support and will auto-organize files. My only complaint with that is that it leaves behind old folders and files. e.g. If I have a few directories of MP3/Flac/whatever downloads with cover scans, it'll happily use the tags to organize the way I like it* but if there are "extra" files they stay put and have to be cleaned up manually.
But it's really a proper Swiss Army Chainsaw for doing everything in one application.
* Proper directory structure is "Artist/(YYYY) Album Name/NN-Song Title.[mp3|aac|flac]"
[1] https://www.strawberrymusicplayer.org/ -- a fork of Clementine, which was a fork of Amarok.