iTunes: on Windows it really is absolutely shit bloatware. On the Mac its a different story. If you import a huge collection it will take DAYS to calculate the gapless playback data. You can use Winamp with iPods (or even better use the ml_ipod plugin).
Cowon: I had an M3 and it rocked. They make some of the best players out there IMO. The FLAC support was great tho it didnt seem to handle compression level 8 as well. The M5L has an amazing battery life, pity they dont make it anymore! They do make the X5L tho which is similar. 60GB only tho. Cowon/iAudio's in general have great battery life.
Zune: Ive heard good things but its not available outside the USA.
The 160GB ipod is an amazing amount of storage. If thats what you want then go for it because I'm not sure how long its gonna be around. The flash players are catching up in terms of storage, and its not just the ipod touch. Sony have release a ridiculously thin Walkman with 64gb.
http://www.trustedreviews.com/mp3/ne...est-to-Date/p1
Archos make what looks like a great Android based mp3/video player with 64GB flash ram too. Its expensive but looks pretty awesome.
http://www.advancedmp3players.co.uk/...blet.4008.html (theres also a 160GB/320GB/500GB HDD version). The 64gb and 160gb are the same price as the ipod touch 64gb.. about 299gbp.
Advancedmp3players.co.uk is where i bought my Cowon M3, theyre very good and have good prices and a big selection. Storage space isnt such a big deal these days. I have an iPhone 3GS/32GB and thats enough. The rest is stored on a 2TB NAS at home. I dont think theres any need to carry all your music around.