Some anime series that have been praised for their character development and relationships include "Naruto," "Hunter x Hunter," "Fullmetal Alchemist: Brotherhood," "Steins;Gate," "Attack on Titan," "Clannad," "My Youth Romantic Comedy Is Wrong, As I Expected," and "March Comes in Like a Lion." These series are known for their well-developed characters and intricate relationships, which have resonated with viewers and critics alike.