Just come across this review of the 1DX and 5DIII vs the Nikon and Sony opposition.
http://www.digitalcameraworld.com/2015/05/26/the-best-camera-money-can-buy-6-top-dslrs/2/
The graphs and images have the 1DX and 5DIII leading the field for S/N for most of the way with the Nikon 810 at the "bottom of the pile". Above iso 400 (my usual range) the 1DX has the best DR with the 5DIII next and the "810 lags behind". The handling of the Canons is best, of course.
http://www.digitalcameraworld.com/2015/05/26/the-best-camera-money-can-buy-6-top-dslrs/2/
The graphs and images have the 1DX and 5DIII leading the field for S/N for most of the way with the Nikon 810 at the "bottom of the pile". Above iso 400 (my usual range) the 1DX has the best DR with the 5DIII next and the "810 lags behind". The handling of the Canons is best, of course.