Guys, many thanks for your explanations.
Currently I am doing my landscape shots, because I have owned Zeiss 21 2.8, EF 70-200 f2.8L IS II, EF 24-105, which are good ( I wouldn't say enough for landscape. However, I am also interested in birds and wildlife, and even football shooting, the problem is I do not own 400mm and plus.
Back to my topic, if I buy 1DX, I can not only shoot landscape, but also wildlife in the future. My question is:
1. compared with 5D3, is 1DX better or equivalent to on landscape shooting?
2. Lacking of 4 megapixels, is it the big gap between 1DX and 5D3 on landscape shooting?
1. The 1Dx is more to carry round and cost much more. I doubt that you will notice the differences in your landscape shots from one to the other. If you can take a good landscape you will be able to with either of these cameras.
2. It all depends what you are going to do with them. I don't notice the difference for what I do. I doubt you will either.
I have the 1Dx, and love it. For the wildlife that I mainly take it is the better camera. Defiantly. But its heavier and more expensive.
For most of my shots the 5D3 is the better camera. It is lighter to carry around and smaller.
Most of my shots are taken with the 5D3. But if I had to have just 1 it would be the 1Dx.
I very much doubt that the pixel peepers and spec readers would be able to tell what camera had taken my images. There is a huge amount of rubbish spoken on here when people try to show how clever they are.
Either camera will take superb shots if you can use it. As will many others.