If one doesn't have a previous lens bias, then Sony might be worth considering. They are the source of the better image sensors available for consumer cameras, Nikon uses some Sony sensors in certain models, and has been for some time now.
As much as I like Nikon they were late to the mirrorless game, but we've been using Nikon for many decades now and have many Nikon or Nikon compatible lenses, so would be more expensive to switch to Sony now, so we'll stay with Nikon.
Earlier the dedicated autofocus sensor was much more sensitive than the autofocus sensors integrated within the image capture sensor on mirrorless cameras, and this was the main reason for the mirrorless poor low light focus performance, however that has now improved.
Today all the cameras are so good and the algorithms for just "pointing and shooting" are almost as good as if someone knowledgable sets up everything before hand. Have a former colleague that is sort of a camera nut, and he has a bunch of the latest Nikon Z cameras (a D850 also) & lenses, yet he says his wife almost always gets equal or better images with her iPhone!!!
The new lenses are also getting much smaller & lighter, especially the new longer reach types that rely on Fresnel elements (have a Fresnel type 300mm that's about same size as regular 105mm and lighter)!! With the post image capture lens corrections capability the lens designers can focus (pun intended) on getting a sharp image at the corners without worrying about vignetting, or some aberrations and keeping the number of elements down which reduces weight.
Anyway, we are seeing a significant shift taking place with consumer cameras, although most of which is in the Smartphones, but as in many things the semiconductor technology is behind much of this.
Best.