Ok, well, here’s my quick experiment. These comparisons are never ever 100% but it does give a good idea. I normalized the settings in camera and then adjusted the Dynamic Range in post. The D800 sensor is more sensitive to light than the Fuji is so I had to bring up the Fuji file and bring down the Nikon. These files are JPEGs that haven’t been adjusted (other than the Dynamic Range tweaks and exported to web size). Fuji was in Pro Neg Std. Nikon was in the default Portrait picture control. These are both the suggested portrait settings from the manufacturers.
To my eye, the Fuji file is much, much more pleasing in the skin tones and over all colour. I guess this is completely up to personal preference in the end. But I could easily shoot Fuji JPEG for people photos for the rest of my life and be happy. To me the Nikon files almost always have a yellow undertone to the skin that must be overcome, which is why I always shoot Nikon in RAW. I don’t know for sure, but I’m wondering if Nikon colour was optimized for Asian skin tones. It would make sense to boost that skin colour’s tonality. But on caucasian skin it comes across almost jaundice to my eye. The Fuji files don’t seem to have that colour push. Maybe the X-Trans sensor is more precise in colour handling. Might just be a white balance tweaking question. Let me know what you think.