I came into this thread quite prepared to praise FFIX though I'm prevaricating now that I've thought a but more about VI.

But I'll stick with IX. While there was an imbalance between screen time and development in the case of some characters (hi Freya), I felt all the cast had sufficient substance to make them strong and interesting characters in their own rights. That applies to the main party as much as villains and other key players (Beatrix and Cid, for instance).