If I was to receive a free iPod, I would take the most expensive one and cash it in. I'm a true-blue, anti-Apple person. I have a Toshiba Gigabeat S60. At the time I got it at Christmas, this 60GB Video MP3 player cost the same amount as an 30GB Video iPod, with additional features, such as FM Tuner, a 1.8" screen, landscape viewing of photos and movies.
30GB Regular iPod
Larger size, more bulky. Not so great to work out with because of its heavier size. and it uses a mini-hard drive. And if you know how hard drives work, you know there's a greater chance of an error if it gets bounced around too much. Nice to watch videos and stuff on, but it's screen is more of a portrait size than landcsape viewing. Cost from newegg: $236.99
4GB iPod Nano
Smaller size, less bulky. Great to have for workouts, walking, and running because of its design. No videos and photos really, but its a great storehouse for music. Cost from newegg: $184.99
If I ABSOLUTELY HAD TO PICK ONE, I would pick the 30GB regular iPod because it costs more, and that means I can return it/sell it for much more $$$ (If I had to keep it, however, I would go with the iPod Nano as my Toshiba is good enough to satisfy all my needs, except for running. Plus, my father would like one)
I didn't vote FYI.