get the color you like the most... get some sanding paper (hope this is the right word for it in english) rub it gently over it... (it will scratch anyways...) now it is allready scratched so you can stop worrying and enjoy the magic of your new iPod
or buy the color you like and leave it in the box... yay no scratches EVER...
or the last option disasemble it... leave the outer shell in the box, put the rest in a little box so you won't break it while takeing it with you... and once in a while open your box with the outer shell and enjoy the non scratched surface...
all these words are written just to tell you: don't think about scratches... they will happen, they only won't happen if you just don't buy one
PS: I would go with the black one
but that's just my opinion... enjoy it whatever color you get...