The variety or cultivar selected for planting will certainly have an effect on the overall flavor and characteristics of the oil, but the characteristics and relative merits of individual cultivars are hotly contested. Although most table fruit is unsuitable for oil production because of yield, size, and oil content there are always exceptions.
This complicated subject is woven happily and inextricably into the unique fabric of the area where each olive variety is grown negating the attitude that one cultivar is superior to the rest. Variety in olive oil as in all things is indeed the spice of life.
Each has its unique characteristics, but some differences are remarkably subtle. Some olives are more durable, while others hold up better to heat. Some are rich, soft and buttery while others are big, angular and complex. The choices are delightfully limitless. Most are not sold as single varieties, except in the regions where they are produced or at specialty import stores. The vast majority end up being part of some generic olive oil blend marketed under any one of dozens of different brands or labels around the world.
There is no substitute for personal experience. Come in and try as many olive oils as you can. When you purchase in bulk from single cultivar stocks you will be surprised and rewarded by the rich variety and quality available at nearly the same price as branded generic olive oil.