Divinity: Original Sin with my friend in co-op.
Interactions between your party members are super fun especially in co-op since you actually talk with your friend's character. Me and my buddy constantly disagree with each other so it's pretty funny. Aside from that, the combat's great fun, the exploration is amazing, the dialogue is great. The only gripe I have is the story didn't get me so far but it'll probably change later. To me, it feels like a combination of Dungeon Siege 2 and Neverwinter so I'm really enjoying it so far.