Someone has to say it: why do people keep using it? If it's not doing the job it's supposed too, or worse, actively deleting your music it's time to scrap it!
That being said, it is also annoying that a lot of plugins (which is what Foobar 2000/DeaDBeeF is based around), like the visualizer ones, only works in either GTK or Cocoa, not both. I don't think the fragmentation of plugins is a good thing. Hopefully they have a plan to deal with that.
It's the best of a bad bunch.
Having the files automatically organized when the metadata is updated is literally the entire reason I've stuck with iTunes so far.
It's more powerful than iTunes and can sync with databases like Discogs and Musicbrainz to keep data up to date.
oh and it's written in python, which means it's quite easy to hack upon it.
Combine it with an amazon cloud storage account and you can sync your library across numerous devices without being locked into any particular platform. It's pretty nice.
Problem is no other applications have access many of these core features Swinsian is nice but I use iTunes Match so I can access my music on phone and I still use an iPod for my car as I find myself in the back country on weekends where cell services is edge at best or simply non-existent.
It makes me sad that's even a category for consideration. wtf
But if your music collection is already sorted into filesystem folders, all you need is VLC!
Having your whole library accessible everywhere (for free!) is awesome, but downloading stuff for offline access is also easy.