Ok, here goes. Not necessarily in any particular order though! Except RoM.
1. Realm of Magic. Nearly 6 years later I'm still totally hooked on spellcasters, and every time I try to make a normal human I miss being able to fix all my problems by waving a wand.
2. Seasons. I keep forgetting that this isn't just the base game, but indeed a pack. I picked up TS4 in spring of 2018, and those first few months I was always thinking, "Man, I really, really wish there was weather." I have a mod that disables the more annoying popup holidays-- Neighborhood Brawl, I hated that my sims are supposed to act totally out of character and go around fighting for no reason, and Prank Day, which just got to be a nuisance.
3. Horse Ranch. They really outdid themselves making this world, and I keep finding myself moving my sims there. And I'm surprised how often I find myself owning a horse, I really enjoy them more than I thought. If I download a ranch build from the Gallery, I do usually have a pest control phase finding all the sheep and goats they cursed me with-- I have no use for those.
4. Businesses and Hobbies. Two game-changing things about it: Build the business you've always wanted, and mentor nearly anything. Creating a new hand-raised overachieving super sim just got easier, because Mom and Dad can mentor the kids through those incredibly tedious skill grinds, Charisma especially. Nice Nordic themed world, but how did they not include a bar? At least they left you room for one!
5. High School Years. Those over-achieving hand-raised super sims usually get saved for later use-- as a teen. HSY made it possible for your teen to act like a teen, and actually meet and hang out with other teens. And then graduate early, and go to university, making DU a lot more useful as well. One of my favorite worlds too, very pretty. I did have to get that mod to disable Prom though.
And the bad:
1. Lovestruck. The game is worse for having this added. Sims find each other unattractive for the silliest most arbitrary reasons, and don't like being told "I love you," unless they just happen to have been given a like for affection in romance styles.
Edit-- How could I have forgotten? Also the skygazing couples who have completely taken over the game. Nobody plants anything at the community gardens anymore, it's hard to meet anyone at public venues, it's all couples snuggling on a bench looking at the sky.
2. For Rent. Even if it did work as intended, just living in your apartment takes too much of your time! And yes, still not fixed.
And finally, some commentary on scoed's picks:
Life and Death: Beautiful world, big comprehensive pack that worked almost perfectly from day one. But I'm just not into the preoccupied-with-death theme.
Werewolves: Fun, briefly, then quickly forgotten. Except for when the game forgets that I checked the option to isolate werewolves to Moonwood Mill, and a rampaging werewolf shows up at the gym and won't go away.
My Wedding Stories: I bought it for the world, and wasn't disappointed. My sims are lucky if I take the time to put an arch down, and forget about an event.
Didn't buy Bust the Dust, and glad I didn't. I only have a few of the kits.
