Well, I think all of them had their advantages and disadvantages.
The Sims 4: Get to Work -> The active careers were a nice addition, but became a bit too buggy and repetitive.
The Sims 4: Get Together -> A great EP overall, the new Clubs System brought replayability and creativity to the game and Windenburg was absolutely dreamy.
The Sims 4: City Living -> I'm not a big fan of San Myshuno because it is very glitchy for me, I don't know why. I really liked the CAS and Build/Buy Mode items that arrived with this pack.
The Sims 4: Cats and Dogs -> My favorite EP so far (quite close to Get Together, though) because I love animals to my very bones. I wish they were selectable though, if only so we can see their needs and traits/learned behaviors, nothing more. Also, vets! I'm a vet in real life, so I guess you can imagine my excitement for this feature. It is somewhat glitchy in my game, but I manage to enjoy it nonetheless.
I can't wait for Seasons! We are so close now!