[mst]

That was quite a gear rollercoaster ride

So, if he's mainly into landscape photography, he doesn't need a fast lens (in terms of aperture) nor a fast camera (in terms of usability). It would seem a mirrorless camera giving a good live view implementation would be the natural choice. Combined with any decent zoom, which is going to be stopped down anyway. APSC sized sensor should not be an issue for the intended usage.

I can't help but wonder if his issues are really with the gear or his expectations. Just assuming, though, no offense intended.

It would be helpful to know and understand in a little more detail the kind of issues he had.