Breath of the Wild does have flaws, and requires a bit of unorthodox work, but GOTY it most certainly is, broadly speaking.
I played and enjoyed the entirety of Horizon and found the monster hunting to be incredibly exhilarating, but there are some real buzzkills, too.
The fact that so many lists here include either Horizon or Zelda, but not both, really gives this debate the smell of fanboy.
To these eyes, the mistakes of Zelda are a byproduct of Nintendo just going crazy and taking risks, while Horizon's are the far more ordinary kind.
Horizon is a solid adventure and a showcase for the PS4, while Zelda is a mold-breaker that really changes how Nintendo is perceived.
I like them both, but Zelda is the fairly clear choice, and probably considerably better than Odyssey, when all is said and done.