What are the two primary motivations for studying a Guru's biography, and which one is considered superior?

Chapter 0 explains that Guru biography texts can be used in two distinct ways. The first is with desire, known as 'Kamya,' which is done for worldly prosperity or to remove worries, calamities, distress, and diseases. The second way is with a selfless mind, known as 'Nishkam,' which is undertaken for the purpose of attaining liberation from the world and freedom from the cycle of birth and death. The text is unequivocal in stating that Nishkam Guru service, being selfless, will always be considered superior, whether it involves writing a Guru's biography or any other type of service.