Personally I’d go with the 11. The screen is nicer on the X, but you get a processor which is two years’ newer on the 11, plus a better rear camera with Night Mode, longer battery life, and a better front facing camera. If you can cope with the LCD and bezels, I’d say it was a no brainer.
Also if the X is second hand, you might experience throttling much sooner than on the 11 due to the age of the battery. Does depend on how old the X in question is though.