Bases on Apple's track record, and the rumors that X was rushed, I expect X to have its fair share of "first generation problems".
Hence, if money is not an issue, my recommendation is to get X with Apples upgrade program; you get apple care+ and in one year you can return your phone and get the Xs.
Probably the 8. Just don't want to carry around anything bigger than that.
I will buy X. I’m interested in developing facial AR app.