The one that no longer exists where banana flavoured candy derives its flavor from.
That's actually a myth. See Wikipedia.
The Gros Michel has a higher concentration of isoamyl acetate, the ester commonly used for "banana" food flavoring, than the Cavendish.[12] This higher concentration is responsible for the myth that banana flavoring was based on the Gros Michel, but artificial banana flavor was not based on any specific cultivar.