There is a certain order in the enumeration of the twelve disciples. Peter comes first. He is the person who first realizes who Christ is (Matthew 16:16). Each disciple has his own gifts and Christ knows these and uses them. Therefore, the quick and impulsive Peter is first. Peter is not better than the others; he made some big mistakes, but his quick insight is something he has been given; that is his gift. Christ puts that gift to use, which is why he is mentioned first.
2 The names of the twelve apostles are these: first, Simon, who is called Peter, and Andrew his brother; James the son of Zebedee, and John his brother;