You can take the main quest and hold it up to any other game in the genre, let alone open world, and it'll trounce all but one or two. The thing is, Wild Hunt disproves that with great enthusiasm. After all, it's a big, big map and they have to fill it with so much stuff. We've told repeatedly that in order to have an open world RPG, we need to sacrifice depth of narrative as well as creativity in quests. In the case of Bayonetta or Vanquish or even Bulletstorm I really enjoyed playing those games but that doesn't mean I couldn't spot the obvious flaws that they had (Alfheim Portals/QTEs in Bayonetta, the story and characters in Vanquish (which certainly had potential), the uh. I enjoy Bloodborne and Rocket League on a moment to moment basis more than Witcher 3 but I don't have a compelling drive to just keep playing them for extremely long periods and that's what a good storyline provides. Open World games have an unfair advantage just due to scope, however most of them fall well short of actually capitalizing on those advantages so it doesn't make a ton of difference in the long run, but this game in particular never fails to impress. So the game is better than everything in the past 10.5 years or so, that seems pretty good to Game's big doe! 2011 GoTY arguments ahoy! To be clearer I think The Witcher 3 has perfectly competent gameplay and the best storyline/characters ever in a western game and the sum of all parts is relevant. Obviously there's other contenders like Metal Gear Solid 3, Super Mario World, Link to the Past, The Last of Us, and Souls Game X but I don't find those games quite reach the perfection plateau. You can say Tetris I suppose but Tetris has always been a cop out.
Super Metroid, Metroid Prime, Resident Evil 4, Vagrant Story, Starcraft. So it basically comes down to virtually perfect games that are definitely better, i.e. I looked at an old list of mine (and an amusing thread) and apparently I put San Andreas at number 4 at the time as it was the best open world game. But it's probably also better than literally every game that came out last console generation.
This game is certainly the best game of the year, I don't think any sane person could dispute that even though the year's not done yet. And yeah I think we should talk about how it stacks up relative to the best games of all time. I just completed the main story, got a good ending with the ideal world state I suppose but perhaps not the ideal character state.