Based on what the Constitution says, the Congress has the most power of any branch. This power has increased over the years as a result of interpretations of some of these powers.
The major power that the Congress has is the power to make all laws. It decides what taxes to impose and it decides how to spend the money it raises. This is a tremendous amount of power. Additionally, Congress has the power to regulate commerce between the states. This, too, brings it a great deal of power because of how interconnected our economy is. This power is used to make laws on everything from health care to civil rights.
Thus, Congress’s enumerated powers make it the most powerful branch of the government, at least on paper.