Having already played Xenoblade and from what we've seen of X, we have a pretty good idea of how the game is going to be, and it looks very promising.
As for FFXV, I really don't know what to think of the trailers we've seen so far. How much of an RPG and how much of an action game is this going to be? Tough to say at this point. There's so much stuff we don't know about the game. To me it's a big question mark. SE knows that they have to redeem themselves after the poor reception of the XIII series and also that they have to get back the Japanese console gamers who've left for mobile gaming so this title is crucial to the long term success of the franchise. Part of me thinks they're going to do everything in their power to make FFXV a success. If the game turned out to be phenomenal, it wouldn't surprise me and if it turned out to be sub par, I guess I wouldn't be surprised either. After the XIII series nothing surprises me anymore.
Like I said, there's too much we don't know about XV, whereas XBX is a safer bet. We know it's going to be amazing. I'm looking forward to both games, but XBX a little more.