iPod all the way. Am i an apple fanboy? maybe. I like Apple, I like their hardware, I like their software, I like their products, I like they way they run their company, and I like them better than Windows. So if that makes me an Apple fanboy then so be it.
iPods work. If you take care of them they will work for a long time. I've had my 3G 20Gig since it came out in '03 and I've only had to reformat it once. It still works like a charm. I even still have the original pair of Apples little white headphones that came with it.
A vast majority of people I know that had Zen players had them broken/ replaced multiple times. No chance i would buy one of those.
The Zune looks cool, and some of the "social music" features seem really cool to me. Is it true that if you come in range of another Zune you can get music from theirs, and then download it if you like? But, I've read somewhere that the sales were not as good as Microsoft had expected. And the iTunes store is already so huge, I don't see how Microsoft could make their service at the same level
Just buy what you want. But the ability to have a "custom background" is kind of a dumb point to make your decision on.