I am struggling with the same dilemma, what to replace my 5C? I still like my 5c and it still works perfectly, but I like to call myself an iOS developer, and it is getting increasingly hard to develop or release for the 5c, being a 32 bit device.
I headed into an Apple store a few weeks ago, thinking I needed an Xr. Liking smaller devices, and being a cheapskate, and the Xr being cheaper (relative terms) it had to be right for me? I failed to buy one. Side by side, the Xs is noticeably smaller. It is also noticeably nicer, being OLED, rather than LCD. I decided the Xs is the one I liked best and that, even though quite a lot more expensive than Xr, that it was better value.
Since I remain overidingly a cheapskate I have not yet bought one, but the Xs does tempt me a lot, even if niether it or Xr will fit in my shirt pocket. Just my opinion. And even if you heed my opinion, do your own research to confirm the “facts” I have stated are accurate.