Which pack has been most influential in your game?

It's Seasons for me, too. I'm a latecomer to TS4, and I think I bought Seasons the day after I installed the base game. I enjoy the changing seasons, and I like the different kinds of weather in various worlds.

My runner-up would be Cats & Dogs. We're pet people, and most of our households adopt dogs, cats, or both at some point. Brindleton Bay is such a beautiful world; it reminds me of the New England coast, which is one of my family's favorite areas.

The other position on the podium would go to City Living. No matter where my Sims live, they always find themselves going to the city...and not simply for the festivals.

I have to say that for three generations my sims had made the islands their home. It’s so beautiful

It's hard to answer since I don't think any particular pack has overshadowed the rest - at least not in a big way. I guess if I was forced to pick one pack that I use something from the most, it's Spa Day, because nearly all my sims do Yoga. I stick Yoga mats in nearly every build, ha ha. I use CAS and BB from everything, although I add a decorative item from Batuu into pretty much every build 'cause I just love the BB (and because that pack gets so much hate; I love to root for the underdog). I also love the new game play that came with Country Living. Chickens, Cows and Llamas, oh my! I want Chickens and Foxes everywhere!! And now we have Werewolves!! I'm still exploring the things that came with that pack.

I'm still exploring packs, too. I've just gotten started with Get Famous, and I just realized I haven't formed any Clubs. Must get to thinking about that.

edited to add last paragraph

Seasons, weather allows you to get out that sweater because you have too now, it gives you holidays similar to real life ones, you can even create your own. It has good clothes and build items as well. Now you have to garden according to the season you're in or build a greenhouse.
Honorable mentions are Cats and Dogs, it gives you plenty of animal breeds to select from, plus you can edit those, it has good items and build items. Get together has a nice club system that has depth, and it has a good world. Thats the one downside of seasons it doesn't give you a new world. But it's still probably the best.

paranormal stuff usually as i love the medium table & haunted lot challenge. also cottage living as it’s good for ordering groceries and going to buy produce.

Snowy Escape and Paranormal in quick succession. The mountain spirits and later the spectres eased me into playing more with occult elements and eventually opened the door to adding Realm of Magic and to dust off the vampires pack again. The progression felt organic, my sims were slowly discovering the bigger picture.

Can you group sims without Get Together? Maybe it's a BG feature.... Besides grouping sims, the clubs are always used in my game, and I love the huge world of Windenburg. Seasons and Get Together, hard for me to choose.

The most important packs for me are:
1. Get Together with Cottage Living
2. Seasons
3. Island Living
4. Snow Escape
5. Realm of Magic with Vampires, Paranormal, Spooky & Werewolves
6. Get to Work with Strangerville & Journey to Batuu

I love the Cottage Living world and game play. But I also have a cat or two in every household. And weather is very important. I enjoy family, so would not want to be without that (can't wait to get active babies as well as toddlers).

And all my favorite sims have the light saber from Batuu, which I love using. The big bar from Batuu is great, too. I have that in Oasis Springs, along with my favorite aliens that came with Batuu. The desert is a good place for them to live, and I enjoyed building them homes with all the stuff that came with that world. My Oasis Springs is mostly Batuu aliens. I think it's funny when they get abducted by the "real" aliens.

I need all the decor items from every pack, and really enjoy a wide variety of choices for furniture, as well as all the build mode items from each pack. So, in that way, I could not do without anything, other than Dust Busters which I never bought. That and just a couple CAS only kits. Otherwise I find I use everything, at one time or another, in one world or another.

I only played vampires and werewolves once, just out of curiosity, but never went back to those worlds, once my curiosity was satisfied. I do like my replacement for Vlad and the realistic wolf pets for the families that have werewolves. Just not enough to actually play them. And I never got around to playing a spellcaster. But many of the items that came with those worlds are useful.

I use the other worlds to populate with sims I want to see in my game, and a place to put the lots I create that give me a wide variety of things to do. So my other worlds are lovely for outings and vacations.

In short, I need everything to give my game its well rounded game play. It was well worth the investment.

I plan on buying whatever they give us in the future, except maybe a kit or two that holds no interest for me. Because my game can never have too much variety.

The occult packs. Vampires, ROM and werewolves. They are the cornerstone of my gameplay.