There are so many amazing manga fantasy cities that it is hard to choose just one. However, if I had to pick, I would say that Edolas from Fairy Tail is one of the best. Edolas is a parallel world where magic is scarce and people use magical items instead. The city is full of colorful buildings, flying vehicles, and quirky characters. The city also has a dark side, as it is ruled by a tyrannical king who wants to drain all the magic from Earth Land. Edolas is a fascinating and complex city that offers a lot of adventure and mystery.