Here's my favorite town/city from each region and why I'd choose to live there!
Kanto - Vermillion City, because I think it would be nice to live in a port with beautiful sunsets. I would get to watch the ships come and go, relax on the pier and smell the fresh sea breeze. Not only that, but there are lots of scenic routes near it that would be ideal for walks. Specifically, the many connected routes that lead to Fuchsia City.
Johto - there are sooo many good choices, but I think Ecruteak City would be the most ideal place. It's rich in culture, the architecture is beautiful, and I would get to watch the Kimono Girls dance. There's a park nearby, the National Park, and if you head west, there's a Miltank farm! I'd love to try a fresh glass of Moomoo Milk. It must be delicious.
Hoenn - this region in general is amazing. There's nature and water everywhere you look! All the towns and cities in Hoenn are so peak, but Slateport City quickly came to mind as my #1 choice. There's lots to do! I'd never be bored. A museum, a shipyard, market, contests, a lighthouse, the seaside cycling road, and best of all, the beach! After a dip in the sea, I'd go to the soda shop for a nice refreshing soda pop!
Sinnoh - Floaroma Town, without a doubt. I think living in a place surrounded by an endless field of flowers would do wonders for my overall mood and health. It's a town with peaceful, quiet vibes.
Unova - Nacrene City would be nice. There's a forest nearby I'd go for a walk, a scenic view of the Skyarrow Bridge, a museum and a relaxing café where I could listen to the man playing the accordion.
Kalos - I would have to pick Laverre City. It's really pretty. I love that fall, fairytale aesthetic.
Alola - Malie City, with architecture inspired by the Johto region. The garden is such an Ecruteak City vibe.
Galar - I'm unfamiliar with this region since I didn't play Sword/Shield and get a feel of the overall geography, so I had to look up the towns and cities. Postwick looks like a nice, peaceful community. It's close to nature, too.
Paldea - Hmm, I'd say Los Platos. A small, quiet community with plenty of wide open spaces, a river nearby, palm trees, an ice cream vendor, and Cabo Poco is close by. I think it would be nice to go on a walk by the cape and look out at the ocean.