Lear’s basic flaw at the beginning of the play is that he values appearances above reality. He wants to be treated as a king and to enjoy the title, but he doesn’t want to fulfill a king’s obligations of governing for the good of his subjects. Similarly, his test of his daughters demonstrates that he values a flattering public display of love over real love. He doesn’t ask “which of you doth love us most,” but rather, “which of you shall we say doth love us most?” (1.1.49). Most readers conclude that Lear is simply blind to the truth, but Cordelia is already his favorite daughter at the beginning of the play, so presumably he knows that she loves him the most. Nevertheless, Lear values Goneril and Regan’s fawning over Cordelia’s sincere sense of filial duty.
An important question to ask is whether Lear develops as a character—whether he learns from his mistakes and becomes a better and more insightful human being. In some ways the answer is no: he doesn’t completely recover his sanity and emerge as a better king. But his values do change over the course of the play. As he realizes his weakness and insignificance in comparison to the awesome forces of the natural world, he becomes a humble and caring individual. He comes to cherish Cordelia above everything else and to place his own love for Cordelia above every other consideration, to the point that he would rather live in prison with her than rule as a king again.