How about this: games by metascore NOT available on the other console:
Code:
score PS4 Xbox
90+ 3 2
80+ 21 3
To Sony's credit, they have done a great job getting indies onto their console, and they have also done a great job porting their PS3 and Vita downloadable titles to the PS4.
However - if you look at just
retail releases, this is all of the games with an Metacritic score of 75+ released that are on one console and not the other:
PS4:
95 - The Last of Us Remastered (port of PS3 title)
86 - Final Fantasy XIV Online: A Realm Reborn (also on PC)
83 - MLB 14: The Show (also on PS3 + Vita)
80 - Injustice: Gods Among Us - Ultimate Edition (also on everything but XB1)
80 - inFamous: Second Son (legit exclusive)
XB1:
86 - Titanfall (also on PC)
86 - Forza Horizon 2 (also on X360)
79 - Forza Motorsport 5 (legit exclusive)
78 - Dead Rising 3 (also on PC)