Btw: Canon still has no competitor to the D800E. The 1D line is twice the price of the D800. Maybe Canon will be able meet our wishes in 2014 (high MP Cam @ moederate costs, 7DII,...)
BTW: Nikon still has no competitor to the 5DIII. The D4 line is twice the price of the 5DIII. Maybe Nikon will be able to meet its customers wishes in 2014 (high ISO, Low-Noise Camera at fair price, D400...)
And, if high megapixels are so wonderful, why doesn't Nikon put a high megapixel sensor in its flagship?
Since you are prefering the Canon 5D3 to the D800E I assume you have shot with the D800E for about a year and compared it to the 5D3. I have the 5D3, D800, and D800E and put these cameras on a horizontal bar and tested them side by side of the same subject at the same time. I've also tried to move the Nikon glass to the Canon camera but I couldn't quantify the aperture because Novoflex doesn't put F stops on their lens converters.
If you make small prints I could see why you might like Canon better if that is what you've been shooting. However I shoot landscapes doing 3 foot by 2 boot wall prints for commercial spaces and galleries. The original poster has it right, Canon doesn't compete in the large MP area with Nikon. The Nikon's dynamic range is great. I shoot outside on a tripod and keep my ISO low. I can shoot either brand on any day. I choose to shoot Nikon's now even though I'm waiting for Canon to produce a high MP camera so I can use Canon's 17 and 24 tilt shift lenses which are superior to Nikons. Nikon 14-24, however is a joy to use. We would all benefit if Canon felt some pressure to compete with Nikon. Even my D7100 is able to produce excellent large prints due to the lack of an AA filter. I'm waiting for Canon to give me something to buy. So far no luck.