Concerning quality, FLAC>OGG>MP3.
Concerning size(smallest first), OGG>MP3>FLAC
Since the fuze and the clip both support FLAC and OGG, it would be best to encode your songs in OGG because you get the same or even better sound quality for almost half the size or less. Of course it’s personal preferrence though.
If you would like to archive your music, it would be best to encode in FLAC at the highest quality setting.
