GFX all the way
I used an H4D-40 for years. While I loved it, the GFX is much more capable camera for your needs. Off the top of my head, it’s smaller, lighter, great lenses that are as expensive new as H lenses are used, better high ISO, movable focus point will go a long way for portrait and group shots, AF adapter with cheaper third party lenses, better AF, , etc etc etc