Amvidia Tag Editor includes album covers and more. It is the best tag editor for FLAC, MP3, WAV, AIFF and any format you can imagine. There is a trial version, but the paid license is worth every penny. You can customize all the information you want to edit; you can edit in bulk. There are also options to retrieve information about the songs in the folder and iTunes or download directly from the internet. The application is very light and fast. You can even rename the music files from the information contained in the tag columns. The program allows you to move the columns of information, just like in the Finder, which makes it much easier to edit the cells. As for the covers, you can use images saved on your computer or drag images directly from Safari, Chrome, Firefox or any browser of your choice. There are a multitude of items that can be edited, much more than in other applications. You can edit composer, comments, encoded by and copyright, for example. You can also search the information contained in cells directly on the web: on Google, Genius, MusicBrainz and on Discogs. The Tag Editor also indicates which infringement cells you have already edited. All of this without interfering in the audio quality, bitrate or file size, as other programs do.