Witcher 3. Never have I been as immersed in a game as the Witcher 3. There are even secondary quests in this game that have a better plot than some games I've played.
Improved upon everything the Witcher 2 did. I'm going to play them both again, one after another during a dry spell next generation.
I probably spent the most hours on Titanfall. Easily the best multiplayer I've played since halo 3. If it had a more fleshed out campaign, could have been my... GOTG.
Easily the best mp I've played in the decade but the nod goes to the Witcher 3.