I still didn't build a system yet, and as I am planning to start building one now, I have to know which company has the best tools (ie, cameras and lenses etc…) for this type of photography that might as well include HDRin as well. You know it's a long commtiment usually when you choose one of these brands.

You have chosen two excellent cameras here and either will take outstanding pictures for you of the landscape type photography you are describing.
You seem to be asking an opinion here and of course I will be happy to give you mine.
I am working professional photographer and have owned a commercial studio for over 40 years. In my business I have chosen to use the Canon system cameras for several reasons, and I am quite partial to them.
Canon makes a 10 to 22 mm lens, and although I use mostly Canon 5D cameras in my business, I also keep a Canon 40 D just so I can use this particular lens for the landscape type pictures you are describing. The Canon 10 and 22 mm lens notonly is great fun to use because of its extreme wide angle and interesting perspective capabilities, but it is also the best wide angle lens I have ever had the privilege of using. Its results are extremely crisp, contrasty, and sharp, and it has very high resolution. I have never used a better wide-angle lens!
As far as I know, Nikon has nothing available that will compare in quality and resolution to this particular lens! If you do go this route, you will probably never regret it!
If you would like to see a few examples of pictures taken with this lens, the last three pictures in my photo album in this group (d5canon Photo Album) from Las Vegas and from the Mojave Desert, were taken with this lens.
Hope this answers helps in making whatever decision you will make.