The president receives more media attention than Congress because, for 50 years, that position has been the most powerful in the world. Under the United States Constitution, the president, or Chief Executive, is alone vested with authority to negotiate with foreign countries and to send the U.S. Armed Forces into combat. Given the global reach of American influence since World War II -- and the United States is the only country in the world with the ability to project significant military power overseas in a relatively short period of time -- the President of the United States is an extremely powerful individual.
Over time, other countries, mainly Russia and China, developed the capabilities to also project military and, especially in the case of China, economic power far beyond their borders. Even those capabilities, though, are dwarfed by the asset that the United States can bring to bear on an overseas situation. The president alone has the power to send these forces overseas, despite the constitutional restrictions on his power vested with the Congress and the courts. The use of Executive Orders, which carry the legal weight of law, but are neither drafted by nor passed by Congress, is an increasingly powerful form of executive control.
The president is the "face" of the United States around the world. Individual members of Congress may become highly visible and influential, but the scope of their authorities is extremely limited relative to the president.
The reason for this is rather simple. There is one president whereas there are 535 voting members of Congress. Therefore, it is much easier for the media to focus on the president.
The president is much more famous than any member of Congress. There are many people in the United States who cannot name any member of Congress. Others can name only those members who represent their state or their district. By contrast, essentially everyone in the United States knows who the president is at any given time. This means that coverage of the president will be more likely to attract viewers and readers because they at least know who the president is.
In addition, it is harder to report on Congress because there are so many different members. It is not always clear to the media whom they should focus on if they write about Congress. There is no one, easy person to focus on as there is with the president.
Because the president is known to practically everyone, and because he (or someday she) is the clear leader of the executive branch whereas Congress has many important members, the president gets much more coverage than Congress in the media.