The best Nikon glass is really good, IMO, except of much of the glass in the last decade or so until we reached these last few years. The GFX glass, by reading about it and talking to some users is OK, maybe good, but not at the level of what I am used to and have carefully collected. That, and the need for a wider image circle finds me staying with the Nikon gear I have (which I planned to keep anyway), and I’ll just wait for Nikon to catch up, which they eventually (probably) will.