> Since AFAIK there is one genus I just buy the regular ones.
That's correct, but neither 'organic' nor 'fairtrade' means that it would be a different (better) variety. Organic = not sprayed with chemicals for pest control for example; fairtrade = farm hands not paid exploitative rates (paid more).
(Not that I'm preaching you should care about either more, I'm a fairly price-driven shopper.)
In fact ceteris paribus in general you could argue you might expect that organic variety to be worse for taste, since pest/disease resistance has played a larger role in its selection.
I'm not sure that actually works in practice though, because ceteris never is paribus, it commands a premium, it's a somehow more discerning shopper perhaps/on average, so it's more worth choosing a nice tasting/attractive variety vs. the regular one selected for yield.
4. https://fred.stlouisfed.org/series/APU0000711211