So has a guide on her profile, im not entirely 100% sure how up to date it is, ive been using it for years. My favorite one is Celebration because im all the time needing food items for my pet for the gourmand achievement and they sell pretty fast in shops.
Blue Sky does the Book Nook. Other books are in other shops so in order to get the Vendable ones from them you will need to look around and try others.
Celebration Gift does food, and in particular it will sometimes Vend things that are needed in Baking which is currently a Raffle requirement. Dunno why so many Baking items are above Vend rarity, but they are so this is a low percentage to get high reward if you get it thing.
Ocean Depths Vends clothes so it has the Pond Banded Bikini parts, which are part of a new Achievement and so they will sell. Ocean Depths also has some exceedingly rare exclusive very rare to get items that are worth a lot
Shining Crane does Apothecary items including the Empty Vial. Scroll-scribing is currently a Raffle thing, so this is a way to quickly get you some supplies for that.