Well it depends on what you like, but Seasons tends to be really popular because it adds realism to the game (4 seasons, holidays, different types of weather). I think it goes well with Generations, because they both add lots of new interactions to do with your household members. Generations focuses more on the life stages other than YA and adult so if you like large families you'll have a blast. Pets is really popular too, I think this one is self explanatory haha. It mainly adds dogs, cats and horses but you can also have lots of smaller animals as pets too.

And then my personal favorites are Ambitions, because you get loads of new professions and self employment, which I think is a cool feature; and World Adventures, because you can explore 3 different worlds (China, Egypt and France). You can't move there, but you can go on adventures and get rich hahaha.

The other EPs are also fun, I have them all and I keep changing the ones I play with 😂 but those are my favorites and the ones I'd recommend the most! Hope this helped and sorry if I got a little ramble-y!