The best replacement for d800 is d800e.

The best alternatives to d800 are rated as following:
★★★★★  d800e
★★★★★  d600
★★★★  5d mark iii
★★★  d4
★★★  d610
★★★  d700
★★  d7100
★★  canon 5d mark iii
★★  d7000
★  6d
★  df
★  a7r
★  d3x
★  d3
★  d810
★  d3200
★  medium format
  mark iii
  canon mark iii
  nikon d800e
  nikon d7000
  d500
  m60
  canon 5d mark 3
  5d mark 3
  canon 6d
  nikon d600
  nikon d700
  d90
  t809
  d3s
  d900
  canon 5d mark ii
  canon 5d
  d300
  canon eos 7d

Your alternative for d800 is not listed? Suggest!
Speaking about d800, one probably shouldn't forget about dx lens.

Other search terms related to d800 and their ratings are:
★★★★★ dx lens
★★★★★ dx lenses
★★★★ 24-70mm
★★★ sigma 35mm 1.4
★★★ 24-70
★★★ lens kit
★★ 16-35mm
★★ 28-300
★★ 24-85 vr
★ 28 300
nikkor 70-300 vr
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Google Trends

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d800
d800e
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