I liked Unity' co-op since I could do it as a single player, no other players required.
I liked Black Flag Wolfpack mode, since I could play it as a single player.
The other games, and the other modes in Black Flag I did not love due to the inability to play against bots, which essentially killed my ability to play them. Black Flag on PS4 still has players, but I cannot compete against the 10.000+ hour people.
I don't like playing with other people, especially if I have to compete against them, that is just no fun to me. I barely tolerate Co-op because my target is still the CPU.