Camera Features You Need
Viewfinders
If your camera has an optical viewfinder (OVF), then try for one that
shows 100%. Electronic viewfinders (EVF) are getting better and
better, and have the advantage of increasing magnification until you
can see to focus. The new Nikon D810 has a LiveView that works
like an EVF and is perfect for my work.
Sensors
I have owned a number of DX sensors, less that FF (full-frame). I
don't like them and suggest that a full-frame sensor is the way to
go, and with a high mega-pixel count at that. The 36MP Nikon
D800, D800E, and D810 are perfect. The 36MP Sony A7r has
serious shutter vibration issues. I bought one, but sent it back.