That's interesting, Andy. Do you mind telling us which lenses you have tried and which you like the most?
Here’s a list of older lenses I’ve tried on the Z6:
Fifties:
Micro-Nikkor 55mm f/2.8 (after all these years, still my favorite macro lens for its sharpness and flat field)
Helios 44-2 58mm f/2 (wonderful bokeh)
Takumar 50mm f/1.4 (wonderful bokeh in a different way)
Jupiter-8 50mm f/2 (not much experience with this one yet)
Portrait lenses:
Helios F-92 90mm f/2 (tricky to adapt, but wonderfully soft backgrounds and a nice warm glow to skintones
Meyer-Optik Orestor Gorlitz 100mm f/2.8 (surprisingly sharp)
Wide angle:
AI-Nikkor 24mm f/2.8 (meh)
W-Nikkor 35mm f/2.5 (fiddly aperture, but very enjoyable)