If you're keen on Nikon, definitely check out the Z6/7. The new lenses, even the kit ones are great. There are more native lenses due over the next few years, I'm hanging out for the 105mm macro. I've tried a few of my lenses, including a couple of my macro's on the Z body via the FTZ adapter, but I feel the native lenses appear to render the images a little nicer.
While I use a m4/3 setup more than any of my other cameras, it is purely based on the subjects I like to photograph. Once Fuji, and/or Nikon bring out a mirrorless body with an articulated screen, then things may change. One of the annoying issues for me using the m4/3 system is micro detail, or lack there of. I've looked at hundreds of images on line taken with m4/3 setups including some expensive lenses, and they all appear to me, to suffer the same lack of micro detail.