I just started over with a new TS3 folder and here are the worlds I considered essential and installed in it:
- All the Store worlds - even the ones I have never played much, like Midnight Hollow. That's because of all the assets those worlds came with. (Faves are Lucky Palms, Monte Vista, and Sunlit Tides.)
- Rflong7/13 worlds: Legacy Island III, Glenvale County (it's my go-to build world), Beach City, My Bridgeport, Longview II (No CC, Store items used in some but optional; I have all of her worlds and may end up installing more).
- MySimRealty: Storybrook County (No CC required, Store items often used but optional) I have many more of her worlds and may end up installing more of those, too).
- Costerboi: Angel City (Comes with a CC decorative Ferris Wheel)
- Nilxis: Plavi Raj (There is a separate, merged package file for the CC used in the world; it's playable without it but doesn't look as nice and ditto with having more of his worlds stashed).
- Great Bear by Johnnywr (No CC)
Edited to mention CC/Store content in these worlds.
Edited again to add another world :D