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Not to mention that aluminum (or aluminium, depending on your side of the pond) is 100% recyclable.

Never liked the white plastic. It stains and discolors too. It creaks and groans when picked up, the unibody alu model is just tough and goes about its business silently.
 
Aluminum without a doubt. It feels solid, dissipates heat like a boss and stays clean and scratchless.

My GFs white plastic macbook is ****ing horrible compared to my MBP, it gets noisy super fast, it discolors and small pieces break off the edge. I can't wait for the real MBP revision so I can pass my MBP on to her and she can experience how glorious it is compared to her plastic junk.
 
It's personal preference really. I won't go back to plastic if I can help it. Least not with Apple, they seem to have a problem with their plastic stuff cracking (everyone with my macbook that I knew of had cracks on their handrests and even elsewhere and even the iphone 3G I had apparently there was issues with cracks forming. So I don't trust Apple to either use decent plastic or a form that doesn't stress the plastic too much).

At least with the metal stuff I can be careful and prevent damage. With the plastic, it just seemed to happen (stress cracks basically). And poster above me reminded me. Almost a year with the MBP, it still looks clean. You should have seen how nasty the plastic on my MB looked (after a year it was starting to form stains where the hands were, by three years it was gross).

And I hate white on electronics. It looks really stupid imho (makes it look like a cheap appliance).
 
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