Not to sound like an Ass, but I do wish it was Xbox One Only.
Reason being is that there are a lot of people that can Afford the One, but don't want to buy it because there isn't a point at the moment since all the other games are on the 360 still. and the new games are still coming out on 360.
but I am excited for Horizon 2, I loved Horizon. I hope they add in a few things they didn't have in Horizon.
Don't know what Console I'll buy it for though