I think that Jubilife City and and C.elestic Town has to be the best cities because Jubilife is so lively with a lot of things going on down there, the pokewatch creator
, clowns, the gigantic building with a bunch of things to do, the GTS, and your fish rod. Celestic Town is very mysterious and the hometown of Cynthia. It is also where you learn about the legends and mythical pokemons.