Hi, I’m a pro Editor cutting long form docs for TV / Streaming (think Planet Earth).
I move around edit suites, but am never happier than when I’m on a Mac Studio. The Z8’s etc should be good, but I find them laggy in comparison. My home suite is also a Studio.
Personally, I would look at storage. A large RAID array to work from will effectively make you system agnostic, making any upgrades / moves easier going forward. I also find that Prem reacts so much better when using really good, fast storage. The LaCie Big Discs, G-Raids etc if you want desktop storage, or a 10GbE server if you want to go all in (could even build your own for cheap).
If you are after components, then more RAM. I often exceeded 64gb on my old intel iMac, so 128gb would be my min.