If you had it all to do over again...

I feel fortunate that I never bought My Wedding Stories. I don't cosplay weddings so I never cared about that pack and dodged a bullet.

Of what I do own my main regret is For Rent. I like the gameplay OK, but I only play with it in a separate save file just in case. That makes it feel too isolated so I almost never do it. I am grateful that nothing bad happens with it simply installed so I can use the build/buy items from the pack, I just wish I didn't have to worry about it messing up my saves. 

Otherwise it is hard to say. I don't necessarily actively play with every pack because there are so many but that doesn't mean I never use them or haven't heavily used them in the past. I don't build tiny houses very often but I have one that I actively play all the time. I usually add eco friendly water upgrades and solar panels to save money, but I don't pursue NAP's at all. I like the acting career, but dislike the fame system because it makes it too difficult to build friendships. There are worlds I have never had a played sim live in, but I visit commercial lots in those worlds. I don't know, I just think there is some bit of every pack that I use in some way so it would be hard to remove any of it.

Like someone else mentioned, however, I am trying to actively reduce CC in my game simply because my inventories are overwhelming to scroll through at this point. If I am honest with myself I overdownloaded because it was easy and struck my fancy in the moment but in  truth most of it never gets used.

I don't think there are any packs I would avoid, even the ones I am less keen on, as there are things in them that I do like. Kits on the other hand... I would not bother buying these:

Bust the Dust (only because I would need a mod to use it), Courtyard Oasis, Carnaval Streetwear, Urban Homage, Sweet Allure, Modern Retreat.

Also, I do not yet own Prairie Dreams, Yard Charm & Wonderland Playroom.

I guess if I had to name my worst big pack it would be For Rent.

If I ever have to do a reinstall, here is what I would leave out. I just don't use any of these packs enough to justify putting them back in my game if I had to reinstall.

Expansions -- Enchanted by Nature, Cats and Dogs, For Rent, Get Famous, and Snowy Escape. I would be on the fence with HSY since I love the BB and CAS, but gameplay is boring.  

Game Packs -- Batuu and the 3 occult packs. I just don't love the Sims 4 occults as much as I did in Sims 3.

Stuff Packs -- Spooky Stuff and possibly Bowling Night. 

Kits -- I only have about half of the offered kits so of the ones I own, I would get rid of Goth Galore, Bust the Dust, and Country Kitchen.

I think I haven't really bought content I wouldn't want to use. I don't own HSY, GtW or For Rent from the big EPs. My least favourite EP from the ones I own is probably Eco Lifestyle and if I had to choose I might uninstall it, but I like dumpster diving, freegan trait and some other little things from it.

I don't own DHD and Batuu from game packs and I'm only missing Perfect Patio from stuff packs. I sometimes consider buying the packs I don't own, but I think I'm doing quite well without them.

I have some kits and stuff packs I probably wouldn't need, but most of them were gifts or from giveaways, so I like to keep them anyway. I did buy Spooky stuff and could probably do without it. There are also kits I still would like to own, but I just haven't bought yet.

I don't know that there's anything in my game that I regret. If I wanted a pack for just the CAS or B/B, I waited for a sale to make it worth it to me. I love getting more CAS assets, and if there was a way to get them from some of the packs I don't own, I would probably just buy that section. I stopped using CC about two or three years into Sims 4 and I love to create Sims so the more variety I have, the better. 

If I HAD to choose packs I don't need at this point, the top contenders would be Stuff Packs like Perfect Patio, Backyard Stuff, Luxury Party, Cool Kitchen, Toddler Stuff maybe... but then there is at least one thing, most likely a few things that I use and might miss if I didn't have them, so no regrets. 

There are still a couple of packs I think I want, but I was waiting for a decent sale. Businesses and Hobbies has the tattooing and some really funky hairs and some good clothing that I really want. But I don't really play "business" too much, I'd just use it more to set up for my Sims to visit themselves. Most of my Sims don't even have jobs, lol. (Occult player! 🖤) And I just don't care about pottery. The other pack I think I might like is Adventure Awaits. I do like to play with children sometimes and little kid gangs, lol, and I think there's a customizability to that pack that I might be able to do interesting things with. There's a lot I don't know about it though, but I've started seeing some creative uses for it and I think might "need" it. I think I could make a proper cult camp with it. 😆

I definitely wouldn't have gotten those broken packs: For Rent and B&H, just to disable them.  Oi 

Also I wouldn't have gotten the following due to uselessness, redundant or icky (Yup, I disabled them too):                                                                                                   

1. Eco Living 
2. Fitness Stuff
3. Moschino Stuff
4. Perfect Patio
5. Throwback Kit
6. Incheon Arrivals Kit
7. Modern Menswear Kit
8. Carnaval Streetwear Kit

I'd probably cut Journey to Baatu. I got it because my niece wanted something from it, but she since stopped caring about the Sims. I mostly liked the desert-friendly outfits. But even then, I almost never use them. I hated the gameplay of the pack. So there's really nothing left in the pack for me. 

The only two packs I even kinda regret are Lovestruck and My Wedding Stories.  There are certainly packs that I don't use much from (Get Famous for one) but I played with them while they were new and don't regret the experience.  It's telling that the two I do regret on occasion are the two I thought long and hard about.  My Wedding Stories is less of a regret, though I wish I had waited for it to go on sale.  I didn't want fancy weddings in the first place, so I rarely use the system. (Lots of Eloping at the Romance Festival in my gameplay) Lovestruck... Lovestruck I think about disabling at least once a play session.  I don't because there's a hair I particularly like and a few other CAS and Build/Buy items that are part of my regular use, but I do think about it.

But otherwise I'm one of those annoying builders who uses one or two assets from each of two dozen packs (and boy does it feel weird saying that and knowint it is not hyperbole)  Even Journey To Batuu finds its place in Geeky bedrooms and offices.

It's an interesting question. As I play a pack challenge at the moment, having disabled everything but BG, Seasons, OR (at the moment) and a few packs and unlocking one pack at the time it's fun to see what I miss. So far the ones I find myself missing most are: Get Together and Parenthood

It's a bit harder to answer which ones I regret, but there are packs I really don't feel like unlocking (Batuu, like some of the cas for historical game play but never used the pack as such), Bust the Dust (I didn't even notice that it was off until someone reminded me that it exists), SE (feels cut off from the rest of the game and I never really loved the game play). 

The one pack that I truly regret buying on full price is Dine Out, because the pack is simply too buggy to use without mods. And yes there are a few stuff packs and kits that I never use, but I don't know if I regret them either. 

For Rent.