cowon is better ... http://www.cowonamerica.com
... my i have this http://www.cowonamerica.com/products/iaudio/x5/index.html
model, X5V variant .. as you can see yourself has a lot of support for a lot of music format .. mp3, flac, ogg, wav, mpc etc ... i miss only a mod plugin to be perfect .... you can compare that with iriver offert and judge yourself ... and if you not like they'r software you can use rockbox 'almost as a linux'
alternate OS http://www.rockbox.org
I miss only the lack of radio fm support, but other models have that ... Is only sad that is hard to grab one from you local shop ... is not so widespread in europe ... if you live here ...
when you judge alternatives to buy a mp3 player and if you love linux, and want to support it, the best thing that you can do is to look at what formats is supported BY DEFAULT by that mp3 player ... aac+ and variants!? what!? No way, good bye ipod ... mp3 and wma only!? what!? good bye all that stream of crappy flash mp3 sticks, here you can in clude irivier also ... and so on ... why to not include at least an ogg player plugin!? And flac + wav is a must to be ... All that hardware makers has no excuse to not support it other that has a deal in some form with DRM & Co. friends ... BUT if that mp3 hardware player just ignore all DRM stupidity .... well then can be a candidate ... and a rich support for a lot of media formats is a good sign that this mp3 player manufacturer just ignore all DRM issues ...