Unity is still a stunning a game today. I just played through it at 3440x1440(native support too, which is rare). But in my opinion, I think Unity is the last true AssCreed games. Origins/Odyssey(sucked)/Valhalla all share a formula that is very different than what AssCreed was. I wish they'd go back to Unity's awesome parkour and social stealth systems. Unity might have been pretty buggy at launch, but it now plays so well and runs excellent on PC.
My vote:
Two Worlds, an ACTUAL bad open-world game. There's a lot of edgelords on here choosing AssCreed and Oblivion, like, cmon, if that's the worst OWG you've played, you've either not played many OWG, or don't know what a bad one is.