(rip petalburg and oldale)
Music-wise, Verdanturf is my favorite because I'm a sucker for pianos.
With design and aesthetic in mind I would side with Mossdeep because it's near the only ice area and ice is the best. However, I have this terrible fear of the ocean so my favorite after Mossdeep is Fortree, but I'm scared of heights too. So my favorite is Mossdeep, but I would want to live somewhere normal like Verdanturf or Rustboro.