The grass is NOT greener on the other side.
It may look like it from a distance, but when you get there, you can often find it is only painted on.
Friends of mine with D800's complain bitterly about their greenish coloured screens, the poor auto focussing, especially when you pick a point on ther left side as well as other problems.
I have a 5D3 (as well as a 60D with around 150,000 shutter actuations), and I've never had a problem with them at all. In fact, I am still amazed at what a great all-around camera the 5D3 is.
It really isn't lacking anything.
While the spec sheets and DXO tests may say otherwise, in side to side testing, you'd be very hard pressed to see any differences between the D800 and 5D3.
I shoot everthing from weddings, to parties, carpets, products,interiors, portraits, landscapes - you name it, and the 5D3 always does a great job.
I initially went with the Canon system, because of the their lenses and their lower costs compared to Nikons.
The quality is maybe slightly better with Canon, but as most of us spend more on lenses than we do on bodies, the variety, quality and cost of the lenses is what really swayed me to go Canon, and why I stay with Canon.
This thing of D7000 and D800 having a poor AF is a legend. It's just less noob-friendly or noob-proof than most Canon models, but they work great.
No one says the 5D3 is not a capable camera, but the D600 looks pretty much like 90% of it for 60% of the price. If you shoot low-iso you even have some serious advantage.
If you are unaware you should not spread ignorance. There are autofocuses issues (reported by Nikon users) with the Nikon D7000, D800 and D4. Google D800 autofocus issues or search on youtube. There IS a definite and undeniable problem and it is not a few random isolated owners. There are numerous threads on nikon or photography forums. There are countless D800 owners whose D800's have been sent to the nearest Nikon service center for the issue, some multiple times, with many coming back the same as if they were never touched or in worse condition. Imagine you pay $3,000 for a camera or any piece of equipment and it malfunctions in a way that honestly hinders the purpose you bought it for. You would be more than quite a bit upset about the matter.
Here is a well respected Nikon photographer who documents in detail his supposedly fictionary account of his problems with his D800. Photos of what his camera was taking etc. What is even sadder is he sent his camera to Nikon services, they "fixed" it and it came back with the left autofocus points being somewhat accurate but having zero accuracy in the center and right!
In the second link, he does research on the matter and he is finding that approximately HALF the Nikon D800 bodies he has been inspecting etc may be afflicted with AF issues.http://mansurovs.com/anatomy-of-a-nikon-d800-fixhttp://mansurovs.com/nikon-d800-asymmetric-focus-issue
I go to photography school and one of my best friends happens to shoot with a D7000. He is currently affected by the legend-ary D7000 autofocus issues. He is not a noob who should be blamed for obvious user error. His camera misfocuses and misfocuses quite frequently. He mainly shoots portraits, for a living as his occupation, and when he intends to lock focus on the closest eye and achieves focus confirmation, his shots may come out inches out of focus. He does not find this funny one bit. This is already after he has applied AFMA etc. He sent his camera to Nikon services, where they inspected it, claimed they fixed it, and returned it to him. He says it is ever so slightly better but he currently descirbes his beloved camera as one equipped with 39 autofocus points that help him capture 16 megapixels of blurriness! He laughs about the matter, only because right now there's not much else he can do. He will be sending his camera back to Nikon in hopes that maybe they will fix it, if they can, before his warranty expires. He now has a vastly greater appreciation for the basic things like autofocus. A camera that autofocuses properly is a priority in the next camera he purchases. We all don't fully appreciate things until we don't have them anymore.
On another note, I also have another friend who shoots with a D7000 who reports inconsistent focus issues.
So, please, do not spread false information. It misleads others into disbelieving those who are experiencing the reported problems, as if they were liars.