Of all the powers that the executive branch has I think the most important would be the power to veto proposal of laws. The president of the United States is the head of the executive branch. The power to veto laws has been used 2572 throughout history. The president at the time of each veto is who's responsible because the president is the only person who has the power to do that.
To me the executive branch is the most powerful. The president is head of the executive branch and basically runs the country. His ability to veto laws is the most powerful to me because he gets to choose the rules that every single American has to follow. The president is also able to negotiate foreign treaties, appoint federal judges, grant pardons, and appoint federal posts such as members of government agencies. Although, every branch is pretty equal power, but the executive branch has more overall power.