Go for iPhone 8 / 8 Plus.
The price difference in my opinion is too big for X.
Not that X is bad, but real world usage there is no difference between 8 and X, due to the similar internals.
Secondary camera having OIS isn't that big of a upgrade either as the main cam is the same.
FaceID works relatively well, but TouchID is still very very solid.
Screen is better on Plus compared to X, regardless what they say about OLED, the screen real estate is a big difference.
You'll save much money going for the 8, and with minimal depreciation, you can sell it next year and get iPhone X1 or whatever, which is likely going to be a cheaper entry price point.