I genuinely loved the second-generation Zune. The aluminum case felt lovely in the hand, it had swipe-based momentum scrolling before that was common (without even a touchscreen!). It had a matte paint on the front that felt almost like velvet, the buttons clicked nicely, the UI was both gorgeous and practical, the desktop software was the same (after the first couple revisions). I was really sad when mine got stolen from my dorm room a couple years after I got it, even though I had a smartphone by that point.
Bonus entry: the GameCube controller. With that huge, luscious analog stick and that huge, luscious A button. And the overall shape fit the hand really nicely too. For any game that didn't make prominent use of the secondary analog stick, I think it was and still is the best game controller out there.
I was a huge fan of Windows Phone which based it’s Metro UI on Zune. I miss my Window’s phone dearly. I always felt the UI was far more intuitive and simple compared to iOS/Android.
Re: Gamecube controller: Agreed! It really did (does?) feel like the most ergonomic controller out there, though I do wish they had a z button on the left side.
Also, can't forget the notches in the analog stick area to accurately indicate direction.
I loved my Zune as well (it also got stolen, weirdly), not only because of all the reasons above but even the headphones were of excellent quality and lasted as long as the device did (in comparison, both iPod headphones I've owned broke after around 2 months).
The only major flaw it had was a lack of fonts to display unicode characters! I know it was mostly (only?) sold in the US but wanting to display artist names in Chinese or cyrillic characters must surely be a basic feature.
Bonus entry: the GameCube controller. With that huge, luscious analog stick and that huge, luscious A button. And the overall shape fit the hand really nicely too. For any game that didn't make prominent use of the secondary analog stick, I think it was and still is the best game controller out there.