In my opinion, considering that I have visited all areas except Bocca Della verità (Don’t get me wrong, I have built a map and my subscription expired before the map was added.), my favorite would have to go towards Salagalu, with the 2nd being Sacred Valley.
Salagalu is actually my build which has been in progress for 7 months as the majority of time was spent on ensuring that it’s all to my liking. Salagalu was originally conceived as a single city with 4 districts, similar to Umber Point but with all other cities not accessible, but decided to go all out as a full-on sovereign nation as I really want to provide the best experience possible for characters who are willing to take someone on a date or partake in fun activities such as camping, drinking at the rooftop bar, bungee jumping, and skydiving.
The 2nd being the Sacred Valley has to do with the Shrine. Nick sometimes visits there and the characters are actually friendly.