Canon 5d mark 3 issue?

I have nikon d800 and 5d mark 3. I like the way the 5d mark 3 feels in the hand way better than d800. Now the only reason I don't like it. Is every time I try to pull the shadows is see vertical colors a noisy one like a spider net. Did that happened to anyone. Or it's just me. Or it's just a canon thing. Bending and stuff. On the other hand. The d800 does not have this issue. It's just it not good in the hand. And I have big hands. And I like the canon screen and how accurate is the wb. I wanna decide. Which one to keep. Any help would be appreciated.

Robert, its been said that "A picture is worth a thousand words." so why don't you show us some examples of whatever it is you're talking about when using your 5D MK III? Then and only then will we be able to offer intelligent insight as to what is causing you problems.

So EDIT your question and show us some examples.

Add the battery grip to the D800 and see how that works for you.

I too have large hands (glove size XXL) and the D800 with battery grip fits just fine in my hands.

NOTE:

These large hands did not find using the much smaller Leica M2 a problem either