Which of the following factors has the least impact on coffee flavor?

The shape of the beans has the least impact on coffee flavor compared to the other factors listed. While the shape may influence aspects like the grinding process and extraction to a minor degree, it does not have a direct effect on the inherent flavor profile of the coffee.

In contrast, the type of bean is crucial as different species and varieties of coffee beans, such as Arabica and Robusta, have distinct flavor characteristics and qualities. The fragrance of coffee is also significant because it can affect the overall sensory experience, influencing perceptions of flavor. Additionally, the brewing method plays a vital role in flavor extraction, as different techniques can enhance or diminish certain flavors within the coffee.

Therefore, while all listed aspects contribute to the overall coffee experience, the shape of the beans is the least influential on actual flavor when compared to bean type, fragrance, and brewing methods.