why not just put both kits up for sale and see which one sells first?
I also looked with quite a bit of interest at the Fuji - until I came across this :
"Just like the Hasselblad X1D-50c, the Fuji GFX 50S has a relatively simple contrast-detect only autofocus system. This means that if one were to compare the GFX 50S with any modern mirrorless camera with a smaller sensor (say with something like the Fuji X-T2), it is noticeably slow and lenses tend to hunt when there is not enough contrast – all normal behavior for contrast-detect AF systems."
this is definitely true, AF performance is not on DSLR or mirrorless level but there is a lot of grey area here.....in my own testing the fuji AF is slightly faster then X1D....but even that has to be taken with a grain of salt....for some reason the fuji zoom is the fastest lens to focus, i can only compare to the 45 and 120, both of which are slightly slower....
to me the GFX with the zoom is perfectly fine in terms of AF, the X1D is too slow overall (only tested with 45 and 90) and the fuji 45 and 120 are ok but i wish it was faster.....
i am assuming the new sensors will take care of this issue....
on a side note: the A7RII switches to contrast detect at f8 and up and is at that point a lot slower and misses a lot....the GFX is much better in this situations.....i dont know if sony has fixed this with firmware or if the A7RIII has the same issue....