That space gray looks much darker than I expected. Excellent! I didn't want to give up my black iPhone 7.
I'm looking at that colour in the X when I can finally get my hands on one (if ever). Currently have a Jet Black 7+ so was a little unsure with some of the pics making the space grey look a bit light, but I'm happy to see the glass back darkens it a bit. I think it looks quite good on the 8/8+, hopefully the X is the same.
I was considering the silver, but the white back has put an end to that. If it was a shade of silver similar to the 7 I would have been interested.