I am preparing to apply for fellowships in my field of choice, let's call it NotBloodBankology. I plan to ask for a recommendation letter from the chairperson of the department and from our most prominent NotBloodBankologist. For the third letter, would it be better to ask the lowly assistant professor who has worked with me the most and could provide some personal insight into my character but is known to virtually nobody outside our program? Or would it be better to ask a random bigwhig in the department who may not know me too well but is well-known outside our hospital? Or how about the Director of Surgical Pathology who knows me moderately well and is known poorly-to-moderately well outside the hospital? Thoughts?