I prefer the Iriver regarding sound, FEATURES, navigation, battery life, and screen.
The sound is much more dynamic than that of ipod.
Feature wize this players kills any Mp3 player on the market except for few iRiver's other players, and few Iaudio ones.
Navigation is better than ipod's if you like filetree structure, and your folders are well organized. If they are not well organized, then navigation is tedious.
Battery life is way better than ipod's, but the drawback is a need for bootup, rather than a standby mode.
Equalization is way better than ipods, and they don't cause distortion even at the highest DB settings, unless the headphones can't handle the Equalization.
Screen also is packed with info.
On Ipod however I prefer it's simplicity to use, looks, and the famous clickwheel (very important in my opinion). The sound is also very good however I prefer that of Iriver.
If size is a concern the Iriver and the ipod photo are about the same size, however Archos Xs200 is supposed to be 20GB measuring the size of most 20GB players.