- There is no perfect camera; all models have strengths and weaknesses.
- I would start with thinking about the lens ecosystem. Which brand provides
You have high-quality and good-value glass that fits your criteria? You want OEM only glass or access to 3rd party? Nikon is famous, among other things, for the excellent longer lenses.
- When it comes to the Nikon Z6 III - I think many/most people would agree that it is a best-buy in its segment these days. That will most likely change when the Sony a7V or the Canon R6 III are released. And then change again when the Z6 IV comes out, etc.
- Regarding the Z6 III vs the Z5 II. I'd happily pay that extra $400 over the Z5 II for better handling, less rolling shutter, CF card, 60 fps ff, faster shutter speed, bigger buffer, and better EVF. YMMV.