In “Best lenses for the Canon EOS 5DS R: Optics for travel, wildlife & portrait photography“, DxOmark recommends the 70-300mm L f/4-5.6L and omits the 100-400mm II
http://www.dxomark.com/Reviews/Best-lenses-for-the-Canon-EOS-5DS-R-Optics-for-travel-wildlife-portrait-photography
Apart from apparently realising the huge advantage of 400mm vs 300mm for wild life, all else being equal, they can’t even read their own scores.
On 5DS R
100-400mm II: score 26; sharpness 24 P-Mpix.
70-300mm L: score 25; sharpness 17 P-Mpix.
http://www.dxomark.com/Lenses/Compare/Side-by-side/Canon-EF-100-400mm-F45-56L-IS-II-USM-on-Canon-EOS-5DS-R-versus-EF70-300mm-f-4-5.6L-IS-USM-on-Canon-EOS-5DS-R__1469_1009_368_1009
http://www.dxomark.com/Reviews/Best-lenses-for-the-Canon-EOS-5DS-R-Optics-for-travel-wildlife-portrait-photography
Apart from apparently realising the huge advantage of 400mm vs 300mm for wild life, all else being equal, they can’t even read their own scores.
On 5DS R
100-400mm II: score 26; sharpness 24 P-Mpix.
70-300mm L: score 25; sharpness 17 P-Mpix.
http://www.dxomark.com/Lenses/Compare/Side-by-side/Canon-EF-100-400mm-F45-56L-IS-II-USM-on-Canon-EOS-5DS-R-versus-EF70-300mm-f-4-5.6L-IS-USM-on-Canon-EOS-5DS-R__1469_1009_368_1009