I played a tiny bit more. The side quests and "errands" seem to fall into the same traps as other RPGs. Basically the first one has you kill five rabbits, which is exactly the kind of thing Witcher 3 tried to avoid.
As far back as Witcher 2 CDProjekt tried to find ways around that kind of quest design, usually by making the process deeper (destroy three nests) or adding some quirk to every one of them (solve a puzzle at each one, or make some kind of moral choice). More importantly Witcher 2 and 3 tried to make the tasks in their quests seem less mundane. I point this out because Horizon draws a lot from Witcher 3 and that's exactly what makes Witcher 3 stand out among open-world RPGs.
Haven't gotten my copy of Zelda yet but I hear it's a lot more systemic than most of the biggest open-world games around today. People are comparing it to Far Cry 2 in that aspect. What I'm starting to think happened is Nintendo fused the open-world formula together with some Minecraft-esque survival elements and the latter's totally open structure, and may have even borrowed more of Skyrim's systemic systems than any other game that pulls from Skyrim. Most games that do so seem to only borrow Skyrim's interface and overall quest structure, but not the way NPCs and the world react to the player and each other.
Anyway, before I digress too much, if I get more interested in Horizon for any reason it'll probably be the setting and story. The actual game is a smorgasbord of other games but the setting does post-apocalyptic in a way that's a bit different for video games. I'd like to get into that first town and see the other communities.