The most beneficial historical source for a historian researching a loyalist’s experience of the Boston Massacre would be a personal letter written by a British soldier stationed in Boston to their family in Great Britain. This source would provide direct insight into the perspective of a loyalist during the time of the Boston Massacre, reflecting their views and experiences related to the incident.
The other sources—such as a diary entry by Attucks or a pamphlet produced by the Sons of Liberty—would provide valuable information but would not represent the loyalist perspective as directly as the personal letter from a British soldier. The scholarly article, while informative, would interpret existing data rather than provide firsthand accounts.