GertvB good evening,
owning an EdgeHD 8“ with Hyperstar v4 myself i chose the 2600MC Pro. Look for this combination on astrobin and you won’t find images with a lot of vignetting. To me the images look more than just acceptable.
The 6200 is the most expensive option to buy from ZWO – of course they recommend it. But besides the costs you would need plenty of storage for the images. The more megapixel, the more storage and the more processing power/time is needed.
In general, i would recommend the following tool to find the camera for your needs: https://astronomy.tools/calculators/ccd_suitability
Hope this helps. Good luck,
Olli