Must Have Kits??

I think it depends on your playing style and how you like to decorate your homes. I tend to leave kits unbought until I have a clear idea of how to use them, a sim that fits the vibe, which mean for me a kit can be used a lot for a period, and then not at all. But if I look at the ones that I will likely use a lot regardless of what I'm playing right now, it's probably these two. 

• Booknook kit! My clear favourite. I use that bookshelf all the time, in stores, in homes, in dorms... I like the rest of the kit as well but that bookshelf is probably my one most used asset in game. 
• The new kitchen clutter kit I haven't used that much yet, but I can see myself using it a lot! I also rank it high because of the number of useful objects, like getting cereal from the box instead of the fridge. Without knowing, I think a lot of kitchens will have some part of that kit in it. 

Other kits I really like for a variety of reasons are the following: 

• The greenhouse haven kit I use a lot when having gardening sims - however, I do wish they'd gone the same way as with the kitchen clutter kit. A lot of those objects could have been attached to a functionality, and I wish they were. 
• Blooming room because you can never have too many plants to vary your homes with. 
• The artist studio (I'm playing an artist at the moment, so right now this is heavy in use). 
• Cozy kitsch (so pretty and perfect for mid-century homes, which I'm playing at the moment)

There are other kits I really like, and I use most of them occasionally. While I like the clothing kits, none of them feel necessary the same way some of the bb-kits does for me.