My ideal custom world would have 1 community lot for each found in base game, added with each EP, and special to each store world plus each venue lot from the store. It would also have most of the land accessible for adding lots with space for all sizes. Residences for all economic status and family sizes but less 60x60 or 64x64 mansions. As for CC - except for lots built by simmers, only patterns - no objects. All store items yes.
And someday, if after years of just creating patterns and applying them, and after I actually maybe learn to play - I will also learn to create my own worlds!