For me it is:
- Unova (seasons and lore give the region as a whole a huge push)
Highlights: Icirrus City, Dragonspiral Tower, Abyssal Ruins
- Hoenn (I love tropical places and there is a lot of interesting places to visit)
Highlights: Lavarridge Town, Sootopolis City, Route 120
- Sinnoh (I really like the melancholic vibe of the region)
Highlights: Eterna Forest, Eterna City, Snowpoint City
- Kalos (I love the aesthetic of the region)
Highlights: Snowbelle City, Anistar City, Lumiose City
- Johto (Comfy autumn)
Highlights: Ecruteak City, Olivine City, Lake of Rage
- Alola (Could be a nice place for a vacation)
Highlights: Malie City, Exeggutor Island, Mount Lanakila
- Kanto (Not a bad region, but I am tired of it)
Highlights: Seafoam Islands, Celadon City, Saffron City