Psalm 32- the best Psalm ever written?

It is told of Martin Luther that one day being asked which of all the Psalms were the best, he made answer, Psalmi Paulini (Psalms that have an Apostle Paul flavor), and when his friends pressed to know which these might be, he said,

"The 32nd, the 51st, the 130th, and 143rd. For they all teach that the forgiveness of our sins comes without the law and without works to the man who believes, and therefore I call them Pauline Psalms."

-Luther's Table Talk