Canon 5D Mark IV review done by Tony Northrup against Canon EOS 5D Mark III, Canon EOS 5DS R, Nikon D810, Sony Alpha a7R II, and Pentax K-1. A Nice Video comparison video where you can see the performance of the camera against other professionals mirrorless and DSLRS.
Even after the announcement of Canon 5D Mark IV Tony is preferring to keep the Canon 5DSR for portrait / studio work due to the enormous amount of details camera produces – for more details see the video
Also See
http://thenewcamera.com/best-lenses-canon-5d-mark-iv/
That is no wonder. The 5DSr delivers a better image quality in the ISO range ISO 100 up to ISO 400.