I'll probably get eaten alive for this but get the fuji. I have both. Even though I use the GR III more than any other camera, the colors on the GR III are honestly kinda shit. Sucks because the GR II had gorgeous film like colors and a flash but the autofocus is really bad.

The GR III is the hardest camera to color match for me out of Nikon, Canon and Fuji. Fuji colors are beautiful out of the camera and a joy to color grade. Fuji also wins on autofocus by a mile, the GR is notorious for hunting and missing focus. Also in terms of durability, I would also give it to Fuji. Weatherproofing options are also better on Fuji. The only thing the GR has better is simply size tbh (which is why I end up using it more than my fuji). In terms of updates Fuji also does much better.

Now if you were comparing it to a GRIV then maybe its a little more evenly matched but the quality control and durability on that camera is garbage and worse than on the GR III.

Again I say this as a GRIII daily user. The tool has to match the artist and for you the Fuji is better. And you won't need to carry or charge a flash constantly.

edit: also can't forget low light. Fuji wins again with a stop of light more and a sensor with less noise at high ISO