I've just tested Songbird and it's got a long way to go, even with plugins, to match iTunes. I thought iTunes was light in the metadata editing department, but Songbird is absolutely spartan. They've copied essentially iTunes versions prior to 7. Also known as the iTunes-sucks years. I think they have at least another year or two before they get close to filling in their holes (based on development progress so far).

The Songbird developers have claimed that they're using a "best practices" approach to UI, but it's plain to see they simply used iTunes as a template. It was the source for pretty much every aspect of the Songbird UI.

Anyway, I don't need a manager to do anything but tagging, so I'm fine with using Songbird for nothing more than Lyrics right now. iTunes does everything else better for my music collection (except handle files other than MP3 and AAC).

I've never used a manager to control where/how the music files are stored though. I keep things in Artist/album folders for that and just let the management programs look at the files once I've put them where they go on disk.

After using Media Monkey though, I would strongly recommend taking a look first at the MusicBrainz tools. They're smaller and lighter and seem to be designed for what was requested, tagging.

If I could have iTunes metadata editing pumped-up I wouldn't even look at anything else right now, including other taggers. Unfortunately, regardless of what you want to use, with the current tools available, I think the process will always involve multiple of them. For instance, MP3 Tag, which I've mentioned before, is excellent for being able to see absolutely any tag in your file - as well as being able to create any tag you want, even if it's something completely custom. I need to use this to clear and set tags other programs don't support. Mainly because Slim Center does support and read those tags which can cause issues in my music database.