What is considered the most important power congress holds?

The most important power that the Congress holds is the power to create laws. Any proposed law cannot become applicable until it has been passed by the Congress or rather by the representatives in the Senate and the House of Representatives. In Article 1, Section 8 of the United States Constitution, the powers of the Congress has been detailed. Other than the power to create laws, the Congress also has the power to declare war on a country, establish Federal Courts, raise army, regulate commerce and coin money and also establish the rules for immigration and naturalization.