I beleive that the executive branch is the most powerful branch of government.
The first reason is that he's the commander in chief, and he doesn't need a declaration of war to deploy troops.
He has he implied power over air force.
Another implied power is the president's ability to make an executive agreement, this is different from a treaty and only needs majority vote from both houses of congress.
The executive branch is more powerful than the judicial branch because the president appoints the supreme court justices, and the supreme court only has tertiary power with it's impied power of judicial review.
On paper congress has the most power, but there are so many people with conflicting veiws that they can't get much done.
The president also has the power of an executive order, which is basically a law, but easily repealed by the next president.