If I were to rank the neighborhoods, not counting worlds like Forgotten Hollow that do not have neighborhoods, my top three would be as follows.
1. Bedrock Strait, Oasis Springs. I love everything about this neighborhood -- the low-rent homes, the dust, the low water creek that runs through the back. I have spent so much time playing there that it has come to be emblematic of The Sims 4, and will likely be the first thing that comes to my mind years from now when I think back about this title.
2. Ridgeline Drive, Newcrest. The set of five lots set in front of a nature trail dotted with cookout locations has hosted many of my sims' homes over the years. It currently is used as an area I call Eastpark, with numerous nature-based lots and a mausoleum.
3. Cavalier Cove, Brindleton Bay. I enjoy the non-commercial New England beach vibe and the isolated lots. I have a restaurant that is based on the Wayburry Inn, which served as the outdoor shot model for the Stratford Inn from the 80's sitcom, Newhart.
Honorable mentions would go to San Myshuno's Spice Market, Strangerville Plaza, and Lani St. Taz in Sulani.