what is the best software to paint??
What do you mean by "paint" ???
And are you only interested in CAD software?
I finished a modeling (aircraft), and I want to apply some material on it, I am using catia v5.
is that rendering you ment??
With your CATIA model, you can use APPLY MATERIAL as Jasper said. To see the material, make sure you choose the Material option for the rendering style.