Thanks for publishing your experiences with both. Like you, I was considering the same choice between Sony and Fuji, so I am relieved to hear that the images from these two fine cameras are nearly indistinguishable. I already own a Fuji X-T2, and it is indeed a fine camera, but to use it effectively I would need a whole new set of lenses. I've been shooting Canon for many years and have a wide collection of lenses and bodies, so being able to use my existing lenses (warts and all) turned out to be a powerful inducement for Sony. In the end, I'm selling my Fuji gear (sigh...), and keeping the Sony A7Rii and my beloved Canon gear. The 42 MP images from the Sony are just wonderful to work with in post processing, and they take sharpening very well. So far, IMHO, none of the mirrorless options out there are really suitable for wildlife photography.
P.S. Another inducement is that the Sony body is about 1/3rd the price of the GFX. There is much less cost differential in lens prices, but for me that's not really a consideration.