I have a 30GB iPod 3G (touch-wheel model) that I got as a perk from work.
I have nothing against other models of player out there, but the most useful feature for me is that a lot of car stereos can interface with the iPod through an adapter kit. My Pioneer DEH-P680MP controls the iPod so I don't have to futz with it while driving. USA Spec and Harman Kardon also make kits that will interface the iPod with stock car stereos, provided they have CD changer inputs.
I don't use iTunes. Instead, I use WinAmp with the mlPod plugin. It does what I want fairly well.
Intel Q9450 @3.2GHz, Gigabyte GA EP45-UD3P, 4 x 2GB G.Skill @4-4-4-12
Antec P160SW case (modded), Xigmatek 750w PSU
3x 500GB (RAID-5), , OptiArc 7200S, ASUS E818A3T
Creative X-Fi XtremeGamer, Hauppauge HVR-1800, Radeon 4890