With a 21/22 megapixel camera you can make prints in the range DIN A2 and you can crop in. The pixels on the D800E sensor are very small. If you have small pixel, then you have normally more noise, less light sensivity and a poorer image quality. Same you get if you put 24 megapixels on an APS-C sensor.But the pixels of the D800 are better than the Canon pixels. Especially at low ISO they have lower noise.
wow, it goes RIGHT to his argument of LESS light sensitivity... smaller pixel fit more onto any given grid, so for the sake of this silly 5D3 vs. D800 thing YES, more pixels = more res. but the NEW 22.1mp 5D3 sensor handles light BETTER, period!low iso is a stiffles me in a lot of situations today. I dont always have a tripod for 800-3200 iso shots. All given I'd take the 3 compared to the 800 for my style of shooting anyway.
landscapes, studio, street and weddings have been shot LONG BEFORE THIS SILLY CONTEST!
as far as which is better- what are your end results with the kit you have???