Media Monkey has a much better UI than the programs that work with MusicBrainz, mainly because they've copied iTunes.
However, this is what bothers me about its automatic tag fixing:
Fix Tags with Automatic Lookup and Tagging of album art and other track information from Amazon.
Lookup CD information on Freedb or via CD-TEXT, and find missing track details through music-related sites such as Allmusic.
Amazon isn't a very good source for cover images nor for tag data. Certainly FreeDB tag data really sucks because it's prone to user input errors without any correction mechanisms. AMG is sometimes decent, but it can be very spotty with different releases.
The beauty of the MusicBrainz apps is that if you want you can run a MusicIP analysis on all your music to tag it with a fingerprint. That fingerprint can then be used to find data on the specific tracks even if no other track data is present in any tag.
Personally, I do all my tag corrections manually using iTunes as an editor. I do lookups on MusicBrainz sometimes, but primarily use RateYourMusic.com Initially tag data is populated from FreeDB at rip-time. And I've been doing this for years, so now it's only incremental. I don't think I'd like to manually update an entire collection from scratch, starting now.
