Quality and the quantity of love is measured only by the way one is ready to lay down one’s life for his friend. Jesus proposes only this as the criterion for the love. Love is expressed in many ways by many people and in many relationships. There is only one way and the right way of expressing it and that is by laying down one’s life. This should also be done as friends.
The distinction between slaves and friends are interesting. Slaves may do many things and may even sacrifice their lives for their masters but that is of no avail. The relationship between friends are the best because there total and complete revelation between them. So the criterion for judging a relationship is the measure in which one is ready to reveal oneself to the other.
And the best revelation is the revelation of God. Jesus has revealed everything that he has heard from the father and all what he knows of the father. There is total and complete revelation of God in Jesus. In this sense he is the best friend for all and for all times. He has not revealed anything else but God. He is also the perfect revealer of God.