Songbird, as I’ve said before, is one of my favourite music clients. Although it’s currently being neglected in favour of Spotify, it remains my player of choice for actual MP3 files. Why? Because it’s so wonderfully intuitive and feature-packed, as well as being open-source.
The new version brings massive performance improvements, loads of UI tweaks, better search and sorting, and better ability to cope with big libraries (full of completely legally-acquired MP3s, I’m sure). If you’re still using iTunes to play music, then I strongly recommend you give this a try. You won’t be disappointed.