I like a lot of the more popular places, like goldenrod, Mossdeep, Nacrene etc. Honestly johto hoenn and unova are like the 3 main regions that get mentioned when talking about favorite places (They admittedly have the best overall).
Personally I really like Floraoroma town. It's honestly so fucking comfy for me, it's even got it's own stand alone location that's just a giant valley of flowers that presumably only exists for flavor.
https://www.youtube.com/watch?v=_JvSB0oNRdA 
