As it is today, I believe the most powerful branch of the United States government is the executive branch. The President is the most recognizable figure in the government. He is the one person that is always looked toward in times of crisis. His actions are scrutinized by the public and gone through with a fine toothed comb by the media in hopes of finding a fault. He also has the power to implement policies that effect the entire nation. The President nominates Supreme Court justices, not the Congress. The people that he surrounds himself with, namely the people in the presidential cabinet also have the ability to effect the government drastically through the power that is given to them by his office. The legislative branch has the power to implement legislation but the executive branch can hold their power in check because the President must sign a bill before it can become a law.
The legislative branch is a vast and powerful organization. Although few Senators or Congress people have great power by themselves, but as a group they are extremely powerful. The problem that I see is that it is rare for them to come together as a group. Whichever party has the majority in each house basically controls all of the legislation there. When one party controls the Senate and the other party controls the House of Representatives this can bring legislation in Congress to a halt. The lack of cooperation .
between the two parties is a major reason that power in the legislative branch is stunted. .
The executive branch does not have this problem because the President isn't forced to make compromises to the opposing party, although he sometimes does. The decisions he makes are a result of what he feels is right for the country. He, along with the people that surround him don't have to answer to anybody. They are at the top of the political food chain.