That's the thing I have rented a d750 before to try it out and to me it was a meh camera and at the moment I'm doing a lot of mixed photography such and wildlife and people and weddings and I'm liking the new tech in d500 my other choice was a d4 but thinking of waiting till the d5s come out then I can pick up a d4 on the cheap... glass I have basically all fullframe glass but I don't mind that... I have gotten really good shots with my d7200 but my spare body is d7000 which I don't like so wana get rid of that and have the d7200 as a spare and then later sell that to fund either a d4 or d810
TBH, Carlos I can't make heads or tails of where you are going. You think the 750, the best reviewed camera from Nikon in years, is
meh. You are saving up to buy either a D4 or a D810 which are so radically different and meant for different purposes that what you say just puzzles me.
I would suggest that you settle on your likes/dislikes and then understand the shortcomings of what you have and that will guide your purchases.
In the interim, you might consider just posting pictures for C/C and seeing how people react to them.
Because, in the end,
your equipment is irrelevant to anyone else, it's your images that count.