Seeing how emotional this topic is and the comments generated I will put my two cents worth in…… For me the best single player games have been (not in any particular order) Witcher 3, KCD, the Fallout series, Mutant Year Zero and Atom RPG. All of these games have been both entertaining and challenging. Bottom line, they are fun games.
Totally agree with your picks, though I would also add Sekiro and Metro series to the list, for the full-scale well-rounded entertainment value. 
From last week i am looking for best single player pc games but still fail to find a working link for this. But thank God i find it here thanks Anasako for sharing this amazing and working link with us.
They haven’t done anything modernized for 80% of their archives! For example, they selling SmarSteamEmulator from steam undergorund to ensure a offline function. They often doesnt adding widescreen support (no matter if they would use a hook or not, it would be cool if they were so skilled to ensure that) and they arent changing the direct link libraries! So in the end people still playing with the copy protection in background!
Im with Chessqueen, Witcher 3 is shit. Although I really liked Witcher 2. The story was ok(in my opinion) but the presentation of said story sucked and it felt like it dragged on and on with inconsistent pacing. I hope it rebounds with 4 but like FO4(in comparison to previous titles in the series) it probably won’t. Mainstream would be ok if it didnt mean they dumbed down the games both story wise and with gameplay mechanics.