>>4299801Lens, shooting technique, and processing all matter more than sensor size alone imo. FF just has most of the best options for lenses. You're right that the center of lenses tend to better, but that increase in pixel density also demands more of a lens, and one could argue that makes FF better as it's "less demanding" on the center of a lens. Either way, it still boils down to the lens itself. I've posted a few a/b tests here between aps-c/ff/gfx in the past, and still really came down to the lenses.
Foveon, monochrome, or pixel-shift if you want the best pixel level detail, but they all have their own limitations. Picrel has a 200% crop, all sharpening to 0. Honestly, AI sharpening/enlarging is worth looking into too.