joer Loc: Colorado/Illinois

The op asked for advice and surely won't be limited to the scenario mentioned. The beauty of advice is that some is better than others and you can decide what to take or reject.

DavidPine Loc: Fredericksburg, TX

In studio shooting I would use neither. Z7 or D850.

larryepage Loc: North Texas area

I've mostly stopped entering into these discussions, because they mostly just become a collection of individuals energetically promoting the benefits of the cameras they own and minimizing or dismissing the ability of any other camera to be worth buying. I am making an exception here, because once again there are a lot of "institutionalized errors" being promoted around the D500. Those errors have been around this site as long as I have been a member, have misled me around whether I should consider a D500, and just generally mislead those asking legitimate questions. For full disclossure, I have not looked at the Z6, but I have looked pretty seriously at the Z7 and decided not to buy one.

First and most important, the D500 is not just a sports and wildlife camera. This reputation, I believe, was started by folks who read one of Nikon's brochures about the camera before it was ever physically introduced. While it does have very good focus capability and a good buffer (and uses XQD cards), those are just two of its capabilities. I have shot six different Nikon DSLRs over the years (D200, D300, D300s, D810, D850, D500) and can tell you from experience that shooting the D500 is just like shooting a DX version of the D850. Same layout, same menu structure, same sensor density, same image "character," same construction. I never shoot sports, and only opportunistically shoot wildlife, but I am extremely happy to have finally bought a D500 for those times that the big images of the D850 are not needed.

I have a friend at our local photography club who also shoots a D500. I have never known him to shoot sports, and he doesn't speak of doing wildlife photography, although he has done some just as a by product of being in locations where it is possible. He has won multiple awards in club and state contests, and he even uses his D500 for night sky photography with beautiful results.

I will not tell you which camera to choose. I will strongly recommend that you shop carefully and decide wisely, based on your own knowledge and experience. While the Z6 (and Z7 and D850) offer a few new functions that were not available when the D500 was introduced, it is a very capable camera. It will make every lens you own better but it will also take full advantage of the best lenses that you own.

CHG_CANON Loc: the Windy City

Although Los-Angeles-Shooter remains an active member of the community, he probably doesn't care about a resurrected zombie thread a full calendar year after the original post ....

larryepage Loc: North Texas area

You are correct that this thread started a year ago. But it is also true that it has become an active discussion again, and continues to include some of the same old misinformation that continues to plague discussions on this forum. So I stand by my comments. Probably should have replied to one of the recent posters instead of to the OP to be clearer...

CHG_CANON Loc: the Windy City

The only sure thing about luck is that you can still change to a mirrorless camera.