Yeah Halo was it for me, and probably the only real reason I own an Xbox One (although we'll just say that Halo 5 leaves something to be desired...) I think Microsoft has stumbled recently with console exclusives. A lot of people felt that Titanfall[1] was kind of a bait and switch. People paid $60 or whatever for what was essentially a multiplayer-only game. (The sequel will not be an Xbox exclusive.)

https://en.wikipedia.org/wiki/Titanfall