Hm, well the game definitely improved since it's launch in 2014 till a couple years after, but IMO I will never feel like this game is complete. I think that is due to the lack of depth that the gameplay has. I also do not like emotions. They feel more annoying to me than make the sims feel "smarter" or more alive. I preferred Moodlets and then traits really giving my sims personality. Even the system from TS2 is better to me than what TS4 has.
I definitely think B/B mode is the strongest out of the franchise, but I don't think that should be what is most strong in a life simulation game so those are my thoughts.