My favorite by far is Pets. I'm a little bias, since Cat Person is one of my five traits, and I'm a real life pet/animal owner and lover.
![Grin ;D](https://www.carls-sims-4-guide.com/forum/Smileys/default/grin.gif)
It was my favorite for TS2, but the TS2 version is a major disappointment now, but that's because the pets are uncontrollable.
Second favoirte would have to be Generations. I'm not really a family person when it comes to Sims. I like Single's and pets, but I still love the new objects, and occult creature that came with it.
I would tie WA, AMB and LN third. I like all three, and don't dislike any expansion pack, really. I think with all expansion packs, there are features I like and will use, and other parts of the EP I don't like, and chose not to use those features in my game. For example, I don't like Laundry in Ambitions or Punishments in Generations, because it makes the game
too realistic for my taste. I don't like laundry in the real world, so there's no need to make my Sims do it. They've had enough problems on their hands.