What major issue caused the most frustration among the colonists?

One major issue that caused significant frustration among the colonists was taxation without representation. The British government imposed various taxes, such as the Stamp Act and the Townshend Acts, without granting the colonists a voice in Parliament. This led to widespread resentment, as colonists felt their rights as Englishmen were being violated, ultimately fueling the desire for independence. The rallying cry of "no taxation without representation" became a cornerstone of their protests against British rule.