For me, any color that has a black front. So that doesn't leave many options. It drives me crazy that Apple keeps introducing new colors but gives them a white front. I've never been able to stand white bezels. They're distracting and the design is less clean looking as you can see the FaceTime camera at the top and the outline of where the bezel meets the display. I look forward to having a dark mode someday, hopefully alongside OLED updates, to make everything much darker.