My favorite sets are Classic, Rococo (I think all of its color variants are nice, but the blue/gold one is my favorite), Princess, and Alpine (especially the Wave and Leaf default fabric patterns)!
I would say my favorite in furniture turned out to be items kitchen-related that I would get from those animals in the RVs. That we could invite them in as new residents.
I mixed it up but, as was common, I tended to get food. Furniture items of food. Entrees. Desserts. Very useful.
I also made it a habit to acquire the pictures of the cast of villagers in a given town. And I would use basic display stands—which can be customized—for presentation.
I have to acknowledge that a lot of my decorating has been functional.
Mine are probably the Rococo, Sleek, Gorgeous and minimalist. I really like the styling of all the sets and i have some of those items displayed in my house