Which official is more powerful in Congress, the Speaker of the House or the vice president? Why do you think so?

Speaker of the House.

Other than sitting behind the President at the State of the Union address (rather than the real leader of the Senate), the Vice President does nothing. President of the Senate is a ceremonial role. He can break ties in the Senate, but the filibuster makes those almost non-existent. The President may give him power as an adviser, but it's the same power the President could give a friend. (I use the masculine pronoun not out of sexism, but because most women would have better sense than to accept the job.)

It's been like this since the first Vice President, John Adams, described the job thus: "My country has in its wisdom contrived for me the most insignificant office that ever the invention of man contrived or his imagination conceived."

Of course its the vice president hes the lower one of the president.