What media player can handle both music libraries (AAC, MP3) and videos (AVI, MKV,...)? Since iTunes is not capable of handling many video formats, I'm looking for an alternative that can replace iTunes, Quicktime and VLC.

What media player for OSX is able to:


organize a large music library (ACC, MP3)
play videos encoded in (AVI, MKV)
This only hits your second requirement but, if you ask me, it's the more important of the two by a long shot: VLC. It can play just about anything you throw at it. It has support for play lists (both building and saving them) but it does not do any organization of your media. It is strictly a player.