5D to 5D3 (skipping 5D Mark II) comments/suggestions

I actually feel the opposite, images from from the 5D classic do not have as much pop as the Mark iii, however with that said because it was less contrasty I think the classic probably did better on photos with a large dynamic range. Because it was more faded on traditional portraits and skin tone, and it does really lovely things to skin tone. There is something magical about the classic. I could add the pop but I didn't have to add as much as maybe some others did, as I'm a fan of a little more vintage faded looking photos.

I have felt that the Mark iii is very sharp and contrasty and more colorful, more POP but I am talking about traditional portraits and people's skin and clothing.

You are talking about landscapes so I honestly can't speak to that, but for people's faces and skin the Mark iii is much more contrasty. I prefer the classic still over it, but the mark iii is just fine for me. I have a feeling its the 16MP that made that possible.