As I stated during D:OS2 Vs PoE2 thread back on Obsidian forum, those are different games. A bit like left4dead Vs Doom. What you prefer, will be based on what game you are looking for. From my perspective it is Larian who is behind the competition in their narrative design, companions, quest design, worldbuilding and overall playability.
But yeah, if you are looking for a coop RPG no one does it better than Larian - mostly because no one else really does it. At best it is coop functionality added to a single player game, while Larian adds single player functionality to a coop title.
For me it is the single player that is outstanding. I love the quest design (no fetch quests or other boring quests), the map design (no large, empty boring areas and minimal loading screens), the cinematic dialogue, high quality voice acting, reactivity, custom pc, and having companions with banter, in-depth quests, romance, and lots of dialogue and scenes. Now that nonorigin companions are confirmed, I am hopeful that there will be a range of companions to pick from. These things put it above most single player games I have played.
For me the multiplayer is okay but not having group dialogue like SWTOR has makes it less fun because only one person can participate in dialogue (seems more like single player dialogue).
