We are chanting God's Name as
Hare Krishna Hare Krishna Krishna Krishna Hare Hare
Hare Rama Hare Rama Rama Rama Hare Hare.
The Lord Has millions of holy names and you can chant any one of them and each and every Name of the Lord is full potential. We chant the abovementioned holy Name of the Lord because the name was Chanted by Lord Caitanya the father of this movement of Krishna Consciousness. We follow Lord Caitanya's footprints to achieve very quick result. I would advise you also to follow the principle. Krishna means the most attractive reservoir of Pleasure. Who does not want such pleasure? Therefore we want Krishna and nothing more.
(Srila Prabhupada's letter to Mr. Dambergs (senior) -New York , 12 April, 1967)