My favorite open world game is easily Legend of Zelda: Breath of the Wild. The world is just gigantic, and the gameplay is seamless and smooth. It's just the most fun open world game I've played that I can just explore and do no objectives, and still have fun. I love the Fallouts and Elder Scrolls games, but if I'm not doing something towards an objective, I feel like I'm wasting time. I never wander off the beaten path and simply explore for the hell of it in those games. I know I really should but for whatever reason I don't. But in Breath of the Wild, just wasting time is part of the enjoyment for me. RDR 1 & 2 and the GTAs are good runner ups, as I occasionally like exploring the cities and wild west, but I guess I just enjoy the art style and lore of Zelda more.