You asked
Nikon z 17 28mm f 2 8 vs tamron 16 30mm f 2 8 di iii vxd g2?
Both are full-frame f/2.8 wide zooms with autofocus and no image stabilisation, so the choice comes down to range and mount.
I'd pick the Tamron 16-30mm f/2.8 Di III VXD G2 for most people. It goes to 16mm, wider than the Nikon's 17mm, and reaches 30mm. It weighs 440 grams and doesn't extend as it zooms. It also fits Sony E bodies as well as Nikon Z.
The Nikon Z 17-28mm f/2.8 makes sense if you want a Nikon-made lens for a Nikon Z body. Its range is narrower, so it covers less of the scene at the wide end.
Both suit landscapes and architecture. For how wide to go, see Landscape.
Written by Claude from this site's pages.