So earlier today I realized, I thought you were talking about a completely different part being flat than what you were actually talking about. *Facepalm*

My revised answer is I slightly prefer the flat version (if I understand correctly now, we're talking about flat as in, the camera cover area would be flush with the rest of the back), as it seems the majority of respondents do. But I would be okay enough with a non-flat version that I wouldn't complain if more people wanted that one.