The reason I have a D750 and not an 800 series is because the D750 does so much so well. in a more convenient overall package. The 800's and above seem a bit more specialized to me whereas the D750, if Master at None, is a true Jack of all Trades. But then for me, it was obvious; I knew the minute I saw the spec's the D750 was the "right" camera for me. I hate to say it "called to me" but that's sort of how it felt. If none of the camera's you're thinking about are doing that for you I'm not sure what to tell you. I'm sure the 800's are fantastic but I would certainly give serious consideration to the D750 if I were you.
Congrats, in advance though, on whatever you decide. Such an exquisite agony, these choices!
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