D810 I thing best in AWB.
For me the main improvement I was hoping to see in D810 was AWB and Nikon delivered. It is night and day from D800. Personally I believed that D810 has the best AWB from all the Nikon cameras I have used in the past. I've only used D800, D700 and Df. I am no expert in color correction and I struggled a lot with my D800 but 810 is making life easy for me. Df was another easy one to work with but I think D810 has taken it to a different level.
I shoot a lot of African events and colors are usually all over the place. With what I'm seeing with D810 I can now leave home without my grey card or ExpoDisc and still manage to pull something nice without too much fuss with WB. I shot an event last night in an ugly place with bad lighting and to my surprise when I got home the pictures came out nice.
I will usually use flash to overpower everything but this time I shot the whole event with no flash. Good job Nikon. I am fan.