I like FF4's cast best, especially after playing through the After Years and fleshing the characters out more. I like how the characters embody their classes. Kain and Rydia were iconic and pretty much defined Dragoon and Summoner for the future games. The twins were awesome, this coming from someone who usually finds child characters annoying. I like how most of the characters are tragic and flawed, but succeed in spite of their flaws over the course of the game.