>>44761664Fav - probably Hoenn. It's the first region that felt big, alive and with lots of secrets to find. Kanto/Johto were so "stylized" and simplified due to technical limitations that even to a child, there was a limit to what I could expect from them.
Oddly enough, none of the games set in it are my favorite.
Least fav - most likely Galar. It's probably a little subjective since the disappointment and butthurt from SS is still somewhat fresh, but objectively there's so little to do outside of the ugly as sin open area that I can only remember it for its character designs, the first route and maybe a couple of cities - and all the frustration, of course.