We won't know for sure until more people use the phone in the wild, but if you are comfortable discounting the obvious disadvantages, XR is a superior phone all around.
Reasons why 8 Plus might be better for you:
No telephoto lens on XR
Lower resolution screen on XR
Whether you prefer Face ID or Touch ID
Lack of 3D Touch on XR
But XR is better at:
Much better rear wide angle camera (especially in terms of exposure and video stabilization)
Faster performance
About 1.5 hour longer battery life
Larger overall screen but smaller physical size
More LTE bands, especially for T-Mobile users (cellular performance should be on similar enough since they have the same antenna design)
For all things camera, the XR is objectively better (Larger sensor, stereo video recording, new software effects) while for mobile reception I guess we won't know until the XRs are in people's hands.