>>42468804Sinnoh is the largest in terms of geography, based on the equivalent area of Japan. Hoenn has the most routes and they're pretty sizable.
Alola and Galar only feel big because of the changes to scale, the routes are actually much smaller (and Galar has only ten) and have a lot of empty space. Wild area isn't even that big and we have no idea how big the DLC maps will be.