Silver/White.
Don't like the space gray color. If it was black on black, yes. I have had a black iPhone since the 3G and switched to white with the 5S and loved it. I just like the clean, simple look of it. Black is everywhere and just boring to me now. I was like many people that thought the border would distract/drive me crazy. It hasn't at all.
The only thing I don't like about the silver is the fact that the bands on the back are not white. They are a lighter gray. Not sure why they did that. The gold phone has white bands. It's irritating they did not do the same on the silver 6. 🙁