Ryuji is my favorite character (I'd probably put my head-canon version of Mastermind Sojiro ahead of him, but it isn't true to the game's presentation). I don't think he is the best member of the group, but as a character in a story he is phenomenal. He has a serious issues with seeking approval. His dad left and it has caused emotional scarring. He tries to seek approval as a Phantom Thief (he very consistently speaks from that stance) and loves it when he gets it. Eventually, that rush fades and he realizes they don't love him but some nebulous idea they don't really connect to anything. People outside his clique still treat him like crap. So he begins suggesting eventually unmasking themselves so that he, Ryuji, would receive that approval directly. Ultimately, he gets over it and finds approval in himself and in the people that matter to him.
He deals with real teenage issues caused by realistic and common trauma and grows in ways that can help players see the logical process to truth for themselves.