This "best line-up in Xbox history" thing was a mistake. They use this to talk about exclusives...
Forza 6, Halo 5 and Gears Remastered: the old cycle. As a Xbox One owner, I'm disappointed with this line-up.
Rare Replay: collection of old games.
Rise of the Tomb Raider: timed.
I think 2016 is the right year to use this slogan. MS has a good line-up in 2015 (better than PS4, in my opinion) but not enough to do all this marketing.