If you only have information and knowledge about one human being in your life, knowing about the Prophet Muhammad (pbuh) is the most beneficial. Everything that he did was beneficial. Everything he said was beneficial. Everything he showed his Companions and the rest of the world was beneficial. No one's life was studied closer and in more detail than his. He let his private life, his family life and his business dealings be the subject of study. He let every aspect of his life even his tears be the subject of study. There is no figure in history whose life, public and personal, is so well documented by eyewitness reports. It is a really enlightening document to study.