BOTW is great, but it is by no means the best Zelda. The bosses are mediocre and unoriginal from each other; they're different variations of the same thing. I thought the Divine Beasts were cool, but they weren't too challenging compared to other Zelda dungeons we've experienced in the past. I like how the game gives you a wide variety of options in choosing how to go about accomplishing a certain task; it gives you an objective, and however you do that in whatever order is up to you. The weapon system is annoying and it made me not want to fight anything for fear that my weapons would break mid-battle. The world is also kind of boring; there's nothing to explore, really. Aside from a few shrines and some lizards or whatever, there's really no point to traversing the landscape. I liked the shrines and the puzzles, but I wish they had made less, but bigger dungeons instead, like older Zeldas. They tried something new, and it kind of worked out well, so I can't really fault them for that.
Horizon is beautiful, both graphically and in terms of its characters and narrative. The story is compelling, immersive, and mysterious, and Aloy is a likeable protagonist. She's strong-willed, independent, and probably one of the most positive examples of women in gaming in recent memory. The world has a ton of stuff to find in it, and although the side quests aren't particularly strong and there really isn't much incentive to do them, I found myself enjoying them anyway because I loved Aloy and her adventures that much. The crafting system is just okay, IMO, but crafting in any game isn't really indicative of overall gameplay, so whatever. I won't fault Zelda for it, either.
In other words, I think you'll really like Horizon and you should definitely play it.