Classic 160 GB free with MBP purchase. My wife uses a 2nd Gen Touch which I use on occasion for the fun wi-fi stuff until January rolls around when I can find out whether I get a Verizon iPhone (hopeful) or I switch to AT&T and get myself a black 16GB and my wife a white one (if they ever come out).
16GB 5th gen Nano is my primary, but I do have and use a 16GB 2G iPhone as well. I'm stuck using both right now until I'm able to replace my iPod Classic.
My main iPod is my 2nd gen 1Gb Shuffle. I run a lot, and this device is a 'best friend' out on the road (alongside my Nike+ Sportband).
I also have an 80Gb iPod Classic and 16Gb iPhone 3GS, but these haven't been used for music in a long time since I listen to 300ohm headphones (Sennheiser HD650s) when I'm at home, and iPods won't drive them properly.
But generally, I alternate between my 3G iPod nano and my 4G iPod nano to listen to long radio shows and podcasts while at work. My iPod classic is used to store my music collection and use it in my car when I want to listen to a lot of music.
The iPhone is a very convenient iPod because u pretty much have your phone with you at all times. Just got to remember to bring your earbuds with you along. For storage though, nothing beats the Classic. You just keep feeding it.
I still rock the 4th Gen black and white. I still love it. When it ceases to work, I'll find another and buy it. Just something great about and iPod with the main function being playing music.
I still use my first iPod more than the others - it is a 40GB 3rd gen. The battery died last year so I replaced it and it is still rocking. I have usefull attachments that don't work on my other iPods (FM transmitter, remote that plugs into headphone socket and the slip case with belt clip that came with it) so it remains the best all round iPod and I just like the feel of it. I have a 5.5G 80GB which also gets used for video but doesn't have much music, then there are the 2G nano 2GB which is nice and small but limited, and the 512MB shuffle 1st gen which is robust but really small. Finally, the iPad I'm typing this on has a little music but is too bulky to use as an iPod on the move.
iPhone 4, though I just ordered an iPod shuffle that I'll be using at night. I like listening to music as I fall asleep, but I'm afraid (terrified) of my iPhone 4 falling off my loft and shattering. So I think a shuffle is perfect for my situation. Plus, I need new headphones and a shuffle and headphones is onl $20 more than just new headphones.