With Assassin's Creed, and a host of other games, I've gotten spoiled with the One's features. It is wayyyy too convenient. Still room for improvement, but better than the 360 (for me).
Regarding Horizon (first one), yeah, it got a bit repetitive, and I don't think I played it for more than 3 months, but the kids loved the environment (free roam, etc...).
We are considering going back to the ONE version of Destiny here. It seems several friends who were nterested in the game are now planning to wait until it goes in the cheap bin now.
As for FH2, we will get one copy of that for sure. Like others, I got bored with the first one after a couple of weeks, but I'm very interested in seeing the detail and gameplay on the ONE and the addition of whether to a Forza game is waaaaay overdue. It'll be a good bubblegum game play. My GF and I tend to play a lot of coop campaign shooter stuff. That is our default go-to whether it be Borderlands, Left for Dead, Call of Duty or whatever. Driving games gives us a nice filler option when either of us want to play solo. Since this is less frequent than coop and we are sharing our copy of FH2, it will be fresh a little longer I think.