Horizon is a really fun game. What I like is that there isn't as much "busywork" like in other RPGs I have played, mainly Witcher 3. There is a good mixture of stealth, combat, and action that makes in fun and engaging. I also like the story of a tribal people that exist far after we have died out, only leaving our machines behind. The people in the world of Horizon seem to not know where these machines came from, only that they must fight against them. There's more to it, but I don't want to spoil anything.
It will be GOTY I think.