You have a D200

  • Like what you've got: stick with it. You can get better cameras now (in features and image quality), but if you're happy, you're happy. 
  • Dislike what you've got: Upgrade. A used D300 or D300s nets you a modest boost in high ISO work, better autofocus, Live View, and faster card writes. That just barely qualifies as a reasonable upgrade. The D7200 and D500 are the correct DX upgrade choices for you, and which you pick would depend upon what you shoot, I think. A D610. D750, or D810 is a long stretch, and would have you realigning your lens selection from DX to FX. 
text and images © 2017 Thom Hogan
portions Copyright 1999-2016 Thom Hogan-- All Rights Reserved
Follow us on Twitter: @bythom, hashtags #bythom, #dslrbodies