I've heard some pretty good things about the AP-F version of the 70-300.
As for the 70-200 f/4? It was my go to event telephoto. I loved it, actually made my FF kit lighter than my APS-C kit.
I took the 70-300mm AF-P out yesterday on the Z6/FTZ. Very satisfying in every way (I carried the combo in the hand - with my hold on the FTZ, not the camera, though I doubt it would have been a problem since the lens isn't heavy at all), and the lens certainly holds up very well on a 24MP sensor; AF was, for the most part, quick and reliable, though at f/5.6 on the long end, it can struggle a bit if scene contrast is low, but that's to be expected. So, no regrets so far, on the contrary ... Just to point it out: The Z6/FTZ combo was considerably more enjoyable in use than the D750 with this lens, and results are more consistent and sharper, too.
Now if only I could find (or rather: rediscover) any comprehensive reviews of how the 70-300mm performs on a Z50 - which is bit of a stretch to hope for, but I remember at least one of those ... Ironically, apart from the reach, the threesome (Z50+FTZ+70-300mm) should make a better hike-worthy (i.e. sturdy and well enough sealed) tele-zoom kit than the Z50 with the 50-250mm ... which would, of course, be lighter by about a pound, but that's bearable in the real sense of the word. Pair that with the Z6 and either the 24-70mm f/4 or the 24-200mm, and you get very versatile setup indeed ... Consider me intrigued ...
Crazy times - sometimes, the market seems to drag its feet, and then, all of a sudden, it appears to burst with options. However, the most important thing for me is this: The 70-300mm further strengthens Nikon's position in my collection, and, somewhat surprisingly, validates the Z mount decision thanks to the great performance of the FTZ adapter ... Nikon really *did* put together a compelling system - they may have been somewhat late to the game, but boy, did they play their cards well ...
M.