“Phineas and Ferb” ran from 2007 to 2015, making it the longest-running show on this list. It definitely earns all of its 222 episodes, though. Each episode follows the same basic formula (though later episodes and specials stretch these limits), so it is a comfortable and familiar watch each time. It also has amazing original songs in each episode. “Phineas and Ferb” is available now to watch on Disney+.