FF4 is a fantastic game on its own merits, but it's especially impressive in the context of the series and gaming as a whole.

I really believe FF4 moved the series forward in a major way, from its heavy story focus to its massive universe. It managed to intertwine each character's story with their actual job, and managed to create a captivating protagonist in a way that FF2's Firion hadn't quite achieved. Most importantly, the fact that we went to the moon shows just how imaginative games were. Incredible.