Personally I say you should pick the iPhone X. Not only does it have a telephoto lens, it also has an OLED panel which can come in very handy, especially at night. I had an iPhone X and got my mother an iPhone 8 last year. The 8 is great, although the 10’s screen was better and considerably bigger.
As you also seem a little concerned about the colour, the iPhone X with its stainless steel frame does hold up without case a lot better. It also is significantly heavier and thicker though.
But the steel does age very nicely. In my opinion. One of the reasons why Steve Jobs liked the iPhone 4 with its stainless steel frame was because he thought the way it ages turns it into a unique but ever-changing personal feeling thing. I certainly agree with that. I rocked my iPhone X in black bare back as well. I would do the same with my silver 11 pro but am too clumsy with the smooth glass back.
Anyway, I think 100 bucks more for the X are worth it. At least they would be for me, solely because the screen this bigger and better and gestures are a lot more fluent.