You asked
Fujifilm gf 19 35mm t3 5 pz ois wr vs fujifilm gf 20 35mm f 4 r wr?
The Fujifilm GF 19-35mm T3.5 PZ OIS WR is the one I'd pick for most people. It's brighter at f/3.5 against f/4, it's stabilised, and it reaches wider. On medium format it frames like a 15-28mm on full frame, and it's the widest GF zoom.
The Fujifilm GF 20-35mm f/4 R WR frames like a 16-28mm on full frame, and it has no stabilisation. If you shoot mostly on a tripod or in bright light, it's a sensible choice, but the 19-35mm is the better all-rounder.
Both fit the GFX bodies on the Fujifilm G mount.
Written by Claude from this site's pages.