I have a 20GB Toshiba Gigabeat. It has a magnesium case and a really scratch resistant screen, which I like a lot. The biggest thing is that it works with my Napster to go. That's an absolute must for me. I really like being able to download as much music as I want and put it on my player for what's essentially the price of one CD a month. Yes I know I'm supporting Microsoft and DRM, but I don't personally mind paying for my music.
I've used about 12 GB of space on it, I've got 2542 songs
To be honest though, if it worked with Napster, I'd probably get an iPod. I wouldn't get one because they're "cool" or everyone has them, though. I'm just a sucker for design, and I like how sleek the iPod looks; that's the same reason I love my Motorloa PEBL phone.