Speaking as a semi-knowledgeable consumer, a large part has to do with the fact that Cuba’s climate functions as a humidor. So from growing the leaf to picking it to rolling the cigar, the tobacco is always in relatively ideal conditions. To a lesser extent the industrial tradition (e.g. multiple generations of hand rollers), and then there’s the pedigree factor much like French **** has been perceived to be of higher quality. I will say that the Cubans I have tried are far and away better than anything else I’ve had, and that I’ll gladly pay double for a Cuban given the choice.