Well, Xbox One has:
- Sunset Overdrive, underrated game highly acclaimed by users.
- Minecraft.
- Halo.
- Gears of War.
- Alan Wake.
- Forza Horizon 2.
- Quantum Break.
- Ryse.
- Ori and the Blind Forest.
- High Quality indies.
- Killer Instinct.
- Battletoads.
- Conker.
- Perfect Dark.
- Kinect Fruit Ninja 2
Sony have (counting games that went kind of unnoticed save the graphics, i.e. KZ: SF, or Knack):
- Gran Turismo, the one I fancy.
- The Last of Us.
- Blooborne, the best of them all.
- Driveclub, ok, but not a console seller.
- Resogun.
- The Order: 1886, fine graphics, mixed reviews.
- Street Fighter V.
- Infamous
- Knack
- KZ: SF
Nintendo does have a few exclusive games, too, and there isn't only a Mario Kart
@DSoup :
- Mario Kart.
- Mario Party 10
- Mario vs DK.
- Mario Maker
- Fire Emblem X
- Yoshi
- Kirby
- Devil's Third
- Splatoon
- Fatal Frame
As I see it, Xbox One has the most varied and some of the bestest. Sony added Bloodborne to their library, which is a plus, and Nintendo are always working on exclusive games. Both are competitive but... Imho, the Xbox One has the edge overall.