Witcher 1 has not aged well. It was created in the Bioware engine that was NEVER intended to be a 3rd person perspective game. So outside of the combat being meh, the camera will drive you nuts. BUT... the story is very good. Its kind of worth playing on super easy just for the story.
Witcher 2 has an amazing story, still holds up graphically, and to me, the combat is ok. But then, I played it when it first came out.
Witcher 3 combat, story, and overall world is amazing. The Blood and Wine DLC is amazing. These days play it with Enhanced Edition mod, and enjoy your time.