You have a D5

  • Like what you've got: Of course you do, stick with it
  • Dislike what you've got: Stick with it. Not exactly sure what you dislike. The only realistic side-grade path is the D810, which means you bought the wrong camera in the first place. Your other choice is to switch to a Canon 1DxII. You'll be giving up body build, vertical grip, battery endurance, and more in order to gain a flash and resolution if you go the Nikon D810 route. You’ll be changing to Canon lenses and controls if you get the 1DxII. 
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