Sinnoh and Johto/Kanto maps had a great art style, and you could generally see the overworld in some semblance of scale. You can see the actual landmarks and the path you'd take through the games.

Then they went to some shitty landmark style for both Unova and Kalos before going back closer to scale for Hoenn and Alola. Also came back with another really good art style.

why did Unova and Kalos get fucked so hard? The worst part is Kalos' art was amazing and a better map would have been fantastic.