Superman wins hands down, no question. Captain America has super strength, agility, and speed due to the super soldier serum he was given back in World War Two -- but this is nothing compared to the powers the Kryptonian (remember Superman is not a native Earthman) were given by Earth's yellow sun and lighter gravity.
Once more, he's gotten stronger over the years and his resistance to Kryptonite has increased, so that no longer has the hold over him than it once did. Superman move at least as fast as the Flash. He is strong enough to move asteroids and such; he can fly; he has his heat vision.
To envision a match between Superman and Captain America is to envision a match between The Hulk and Rick Jones, in other words, pointless.
Now a fight between the Hulk and Superman, that would be an interesting match....