I finished both Fallout 4 (also played Fallout New Vegas for a long time) and Witcher 3 (Also finished Witcher 2), here are my thoughts comparing the two: What I enjoy most in games like these, other than the main story, is exploring and the rewards for doing it. In both games each location is unique and may offer unique loot, all things considered I prefer Fallout in this aspect. In Witcher 3, when you get to Skellige, around 60% of points of interest are chests under water, and that killed it for me. Sure it looks beautiful sailing in your boat while watching the sun go down and all the pretty lens effects and water reflection but after 30 min it gets boring af. Also the loot you get is always crafting materials + some gear which you end up selling or dismantling for even more materials. In Fallout, unless you already crafted your own gear, you always have a chance of finding something better, and it's really enjoyable cruising around. Especially with True Storms mod, I could literally just stand there and enjoy the rain sound. Other than that, the skill tree in Witcher and Fallout are similar enough since they're considered as perks in both games. You definitely feel the impact of leveling up much more in Fallout 4. As for the graphics and landscapes, Witcher 3 I'd say is more pretty looking. Even though this goes down to personal preference I'm more of a baroque/medieval architecture type instead of modern buildings, which are pretty boring imo. And finally, main story. Definitely Witcher 3. The characters are much more pronounced, the story becomes intriguing once you get into it, and well done cutscenes. Especially in the latest DLC, Hearts of Stone. In the end it all goes down to preference. I enjoy both games very much, once I start getting bored running around in a game I dive into the other, although I feel like Witcher 3 has more content to offer.