I love iPods but cant bear iTunes and wanted something that could be managed in Windows explorer and on Linux, so I did all the reasearch a little while ago and ended up with a Cowon D2 – 16gb
Advantages
Huge 50 hour battery life – only recharged mine twice so far, volume output goes mega loud which means it will drive a large pair of headphones, expandable memory via SD card, fantastic sound quality – a lot better than my iPod, Rockbox is under development for it, screen is small but nice and clear for watching films, the graphic equalizer works really well, and there's loads of themes and tweaks you can do to personalise it and of course no need for iTunes!
Disadvantages
Wont plug into ipod docks – which everybody seems to have, touch screen is a bit small and fiddly, not as user friendly as the iPod, can crash when transferring lots of files in one go. People think your mad for not buying Apple.
Did nearly get one of the Samsung players, the one with stereo Bluetooth, but adding the cost of some headphones pushed the price too high, the Sansa players are also pretty good – bit boring looking though.
Also I would recommend Mediamonkey as a great bit of software for managing your music library.