other than the iphone, the 2G nano is my favorite. Nanos are the perfect size and have enough capacity to hold my library. And the 3G nano just doesn't do much for me.
1. Big enough to hold all of my media.
2. Smarter than current iPods - and even smarter than iTunes.
3. Big screen (so far #3 conflicts with #1).
4. Be able to make phone calls with my provider.
Go the 1G Shuffle!
New concept when released and great for running with.
The only thing better IMO with the 2G is the seperate On/Off and Order/Shuffle switches.
ipod mini because it is the only ipod that can easily support 32gb of flash(until 48gb, 64gb and so forth cf cards are released). Not to mention I can rockbox which gives a limited player more codec support.
Gotta go with the iPhone. I know it's not technically an iPod, but it's the ultimate if you ask me... assuming you don't need more than 8G of storage...
I would say the 1st Gen Shuffle, because of it's usefulness as a flash drive.
I also love the look of the red 2nd Gen Nano, and I adore my current 5.5 Gen U2 Special Edition. The red click wheel and black metal back just look so right.