Babylon 5’s genius was the long planned plot arc. The compliant telepath learning the truth and overthrowing the corps. The throw-away Centauri ambassador to emperor. The Narn outcast struggling for their freedom leading them to both political and personal redemption.
The individual character arcs are outstanding. When thrust into the spotlight, some rise to the occasion others wither under it's glare. Throw away events from the first and second season become major issues in later seasons.
B5 is the closest experience to reading a good series of novels that was ever created independently for TV.