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Stainless Steel is more scratch resistant than anodized aluminum and if you do manage to put a scratch on Stainless it is really hard to see.

If you're dead set on Aluminum, Space Grey is probably the worst color to get because scratch the surface on a Space Grey case then the Aluminum underneath shines bright reminding you "Damn!!! Should have got Stainless Steel". Remember ScratchGate with the Space Grey iPhone 5.

iphone-5-scratchgate_scuffgate.jpeg

To be fair, the iPhone 5 was Slate, not Space Gray. Space Gray was introduced to the iPhone with the 5S. I still prefer Slate and wish it were still around. I used the iPhone 5 without a case and didn't have any scratches on it, but I know it was an issue for many.

To stay on topic, go with whichever looks better. I went with Space Gray. Only other option, for me, was Space Black but I'm going to wait to see if these get a yearly refresh before spending $1,100 on one.
 
I've had my space grey sport for close to a month now and couldn't be happier with it.

I did put a screen protector after a couple week just as added protection since you can't see it.

I think the body scratch resistance is not really a factor though in most situations.

Phone is held in a hand. Watch goes on your, so it's really no comparison in that respect.
 
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