Is the Congress more powerful than the President?

Yes, I can say the Congress is more powerful than the president. The president is the head of the executive arm of the government and the commander in chief of the Armed Forces. If you look at how the system of democracy of the United States is designed, you would see that it gives more power to the congress in that, there are many things the president cannot single-handedly do, the president cannot form the budget and sign it into law by himself, the budget must first be debated upon in the congress and after that it would be signed into law.

Also the president cannot automatically nominate someone as member of his cabinet without first being sent to the US Congress for screening and confirmation. And mostly importantly, the president cannot declare a war, though he's the commander in chief of the Armed Forces, it is the constitutional duty of the congress to declare a war. However, the president also has other advantages over the congress.