Personally, iPod Touch.
It depends what you want, really. Want something incredibly versatile, but with poorer design? The Archos may fit your needs.
But if you're prepared to play it the Apple way, iPods are great.
Don't ever buy songs from the iTunes Music Store -- stick to ripping your CDs or getting songs elsewhere. (Like many legal stores online, they mess with the songs so they only play on iPod, or only on Microsoft players, etc.)
As for video and audio listening etc., the iPod Touch is excellent. And the multi-touch just feels so intuitive too. The web browser is an order of magnitude better than any other device's too.
http://www.apple.com/ipodtouch/
Note also that Apple is in the process of opening up the platform so that you will be able to buy lots of new apps for the device, all easily over wifi. Many free.