Which one feels better in your hand, which one is nicer to use for you personally.
Which one if laying side by side on the table would you pick up and take out with you when you have 5 seconds to choose and can only take one
Use one for a day at a time and see how times you find yourself missing something or wishing you had the other phone.
When I sent my Oneplus 5 back last year it was only because the camera was pants compared to the then £629 Pixel 2XL but I loved everything else about the OP5, there will usually be a deciding factor that will make the right phone
(for you) click and stand out for you.