For sure, this.
I have the D5, D850, and the D500. I also have the Z7.
The real questions boil down to two:
1) Will you be cropping more often than not, and
2) where will your ISO be, mostly?
If you're going to be cropping (and, for
most wildlife you will—esp. smaller wildlife), you need to realize that the D500 will actually out-perform
every Nikon camera (as well as non-Nikon camera), up to ISO 2500:
View attachment 1960
Keep in mind, these readings are at DX. If you are cropping, the D500 outperforms
every other Nikon camera, up to ISO 2500.
At ISO 2500,
only the D5 outperforms the D500.
(No, the D6 does not. While the D6 has better advancements in some regards than the D5, the high ISO performance of the D5 still betters the D6, in both low-noise as well as PDR. Forget what subjective reviews say, pay attention to
all actual measurements.) Go ahead and look at the PDR of all Nikon's finest in
this link, shot at DX. (You can compare them all, but make sure you're selecting "DX = crop" mode for the comparisons.
The point being, if you're shooting larger animals, or landscapes, there are many better cameras than the D500.
But if you shooting birds, or macro, or any other subjects
where you're going to need to crop-in — there is no finer camera than the Nikon D500, all across the ISO performance range, except past ISO 2500.
At this point, the D500 is still your best choice, unless you're shooting the D5. (The D500 surpasses all Canon cameras, all Sony cameras, and all Nikon cameras,
at DX, "crop," save the Nikon D5, and then
only passed ISO 2500.)
This is as measured formally, and confirmed by my own experience.
If, however, you're filling the frame mostly, then the D850 is the best camera you can use, unless you're shooting over ISO 2500, where the D5, D6, and Z6 will be the better options.
Study the charts carefully, mixing DX and FX, assess where you're going to be, and choose accordingly.