There are so many good ones, though. How can you just have one favorite? I mean, Madagascar has lemurs, but Crete has ancient toilets and labyrinths, while Great Britain has tons of awesome history and delightful accents, while Cuba has an interesting shape and... well, that's just real Earthly islands, what about Treasure Island? Circe's island? The Island of Misfit Toys?
Nope. Can't pick just one.