I never liked Fallout, which made me not like a lot of Skyrim, Bethesda should have kept the old Elder Scrolls system.
I prefer The Witcher, the universe is much more interesting and the medieval world pleases me more.
Fallout 2 was the only one I really enjoyed.
The Fallout combat system is better in some ways, the story does not surprise me too much and the characters are not very realistic or charismatic, The Witcher has memorable characters and an incredible story, but the combat system is not the best.
In graphical question I do not give that important.
Of course, the books of the witchers are as good as the games.
(Sorry for my bad english)