You asked
Is the fujifilm gfx 50s ii worth buying used?
Yes, I think it's a good used buy. The GFX 50S II is the cheapest way into medium format, and the buying used page makes the general case: a body a generation or two old is often most of the camera for a fraction of the price. The 50S II has in-body stabilisation, which the original GFX 50S lacks, so if you can choose, I'd hunt for the newer one.
Budget for a new genuine battery too, since old ones lose capacity.
For lenses, I'd start with the GF 32-64mm f/4 for everyday shooting. For portraits, the GF 63mm f/2.8 is a lovely small prime. If you want more reach, the GF 100-200mm f/5.6 covers it.
Written by Claude from this site's pages.