Exactly how I feel! I even made time lapse montages and a combat video because I was playing it over again on Very Hard with no HUD AFTER I got the Plat.
You know what really bummed me out, though? Two of my friends wrote if off as basically "Far Cry Primal" and haven't picked it up. I even offered to buy them a copy (they live together) but they seem bothered by my suggestion that its an incredible game
Without thinking about it or planning it, I had played and plat'd Primal -immediately- before Horizon came out, which means I unfortunately played them back to back.
There are a lot of similarities (just having the primary weapon be a bow is a lot when you're putting enough time into 2 open world platinums), though also a lot of differences. There are still some nice touches from Primal I enjoyed (pet sabertooths, oh yeah!) but Horizon is by far my favorite. I didn't actually expect to like Primal as much as I did, but I ended up really digging that too.
I wish I hadn't played them back to back, but yeah, nobody should write Horizon off as FCP. They are very different - FCP is at its heart a FC game, meaning lots of 'base attack' gameplay mixed with a lot of hunting [amped up in Primal]. HZD is not a base attack game... in fact, the few bases there are with human enemies are the low points. Rather, it's pure glorious hunter on mechbot combat.