Expansion Pack- I love the idea of a farming pack. Think this would need to be an expansion pack to really do justice to all the things that could be done- farm animals, a new world with plenty of large lots, new interactions, and recipes. Definitely would want to see nectar making brought back! And maybe with a legit way to grow and care for vineyards? I saw on another thread the idea of a Tuscan inspired farm pack and new world, and I CAN'T stop thinking about that. Browsed photos online today daydreaming about a pack like that. Absolutely LOVE that idea! Also think a farming expansion pack would be cool, because it would be a new thing for the Sims franchise.
Game pack- Romance pack. New interactions and deeper relationship system, more bridal gowns (and gowns in general), and more (and better!) romance animations. Would definitely want ballroom dancing/slow dancing skill! Creating romantic storylines are my favorite, but sometimes they feel flat.
Also wish there was a medieval focused game or expansion pack!!!!
Stuff pack- Cars. I don't necessarily care about cars, but I hear enough people interested in it.
Side notes: I miss the ability to save Sims' stories like in Sims 3, and it still bothers me that Sims don't make money or earn tips while tending a bar in public!!! I also like the new roommate system, but I wish there was any easy way to mark Sims in your household as "NPC". Also really want Sims to be able to own multiple homes.