Note that Thom has a dedicated site for the Nikon Z System: zsystemuser.com
Nikon's Z series of full frame cameras was introduced in 2018, and consists of full frame 24mp and 45mp full frame (FX) options, much like the D780 and D850 DSLR options, as well as a 20mp APS-C (DX) option that slots between a D5xxx and D7xxx.
So What Would Thom Get? Any of the Z cameras are solid choices, so it depends a bit on what you want and need.
DX: The Z50 is the smallest, most travel-worthy camera of the bunch, but none are slouches in that regard. The Zfc is a mild update to the Z50 internally, but externally it grew a bit to accommodate the retro dial-based UX. The Z30 is also a mild update to the Z50, with the removal of the EVF and an articulating Rear LCD being the primary changes. So: you buy a Zfc if you like film-style photography, the Z30 if you're a vlogger/videographer. Everyone else should get the Z50, which remains one of my recommended travel cameras.
FX: The Zf, Z5, Z6, Z6 II, Z7, Z7 II, Z8, and Z9, because of the full frame sensor in them, are bigger and heavier than the DX cameras. Videographers should get a Zf or Z6 II and consider the optional upgrade on the latter that provides external raw capability. Still photographers looking for the best bargain should get the Z5. Most of the rest should consider the Zf, Z7 II, or Z8, depending upon how much they can afford. The Z9 is the flagship of the lineup, and is a versatile jack-of-all-trades, but that comes with a size, weight, and price penalty. Most people are well served by one of the lower models.