Newer varieties tend to be bred for production or resistance to pests and disease, not necessarily for flavour. In the past, Bourbon Arabica was the most common coffee variety in Guatemala. The altitude and region where the coffee was grown. The higher-grown the coffee, the better. This is due to the fact that Arabica coffee, the only species which encompasses gourmet coffees, will only grow at a higher altitude.
Coffee is classified by it's relative density - the denser the finer.
The higher-grown it is, the denser it is. Different regions impart different flavour characteristics, due to factors as diverse as rainfall, climate, and type of soil. Usually, in the interest of greater profit, fine Arabicas are blended with lesser coffees. Some of these blends have more Robusta than Arabica, resulting in a rotgut brew that upsets the stomach. Robusta is a vigorous plant that produces well close to sea level but won't grow at the higher altitudes.