I've got pretty small hands but I am really comfortable with my 6.4 inch Oppo Reno Z, it has all the reachability I need, it isn't too heavy or too light and it's got a large enough display for me.
I used to use a galaxy S4, which has a 5 inch display. I find the galaxy quite cramped and not very usable, but the AMOLED was just as good as the Reno Z, and even had better PPI.
Something that would be pretty frustrating would be if phones get any larger, because I find that the sizes currently are pretty much perfect for everyone, although there should be more options when it comes to smaller phones.
Mood.