I need to eliminate the Foundation and Robot books from my response because I loved them all and it is difficult to single out a specific book that I liked the best. Therefore, I go for The Bicentennial Man. This short story was so successful that Robert J. Sawyer had a similiar novel called Mindscan. Asimov presents a legal case as to when artificial intelligence in fact becomes considered a living entity. It is a story of a robot who wants to be human (like The Tin Man) and studies all the legal definations of being human and then goes about remaking himself to be considered human. There are a lot of compelling legal arguments presented.