Ipad Pro 129 Or Surface Pro X. Existing apps run just fine on the larger screen but they have to be specially optimised to actually take advantage of all the available pixels. The Surface Pro X also sports a 32 aspect ratio whereas the iPad Pro.
The screen on the Surface Pro 6 is a 123-inch touchscreen with a 2736 x 1824 resolution at 400 nits. Neither device is cheap but for a pro device neither is all that expensive either. IPad Pro vs Microsoft Surface.
To keep it simple heres a list.
Size is the bigger differentiator. Apples iPad Pro is similarly pricey starting at 799 for the smaller screen and 999 for the Surface Pro X-sized model. Size is the bigger differentiator. 208 x 287 x 73 mm 774 g.