My first HD MP3 player was an IHP 100..loads of features and didn't use ANY of them. My music is a little off the beaten path, so I don't really even have any interest in a radio. On a whim picked up an Ipod Mini when they first came out, and fell instantly in love. I don't know if it's the 30 mW/channel on the Ipod, but to these ears the sound was infinitely fuller and more listenable. And there's something to be said about elegance, form, and ease of use.
Have since picked up the 15 GB version because I've moved to all Apple Lossless files. There is a difference when you start throwing out high end information to save space, and it's a compromise I just can't settle for. I've employed a good approach suggested by Bangraman, by using smart lists on my minIpod. Essentially they're playlists created from your Itunes library a la a searchable database (an automatically updated playlist that's generated by parameters you set such as myrating, album, etc.). My minIpod only holds my newest albums (they're the only ones I give a five star "rating"), while my 3G 15GB is getting filled up with the balance of my music collection...as I proceed to re-rip it to AL.