I've had multiple iPods and one Zune.
The multiple iPods predated my Zune.
I will never buy an iPod again. The Zune is far more resilient. I've had a LAUNCH Zune and except for that silly New Years Eve snafu, it doesn't have one scratch even after dropping it multiple times and works like a charm.
Add in WiFi, the radio, and the Zune Pass and you have a better product.
I much prefer the interface and the lack of that stupid touchwheel as well.
edit: Sorry, I think my tone is a bit harsh here, but it really does kind of pain me that the iPod is so much more popular. The Zune is so much better built, in my honest opinion, and I've used multiple iPod models.