Simply put; play Final Fantasy 6 if you haven't already!
The story of Final Fantasy 6 involves a girl with magic powers. The evil empire (Yes as FF has already told us, all empires are evil!), has manipulated this girl who is known as Terra. Many fear the empire and form a resistance in order to prevent another War of the Magi. The story involves a variety of character, one of which probably has the most characters playable to date (only to be beaten by FF4). Things change when Kefka (The main villain), gains control of an enormous power of magic, soon the party is lost amidst the ruined world and it is up to you to gather them and fight Kefka. Overall, the story is solid. While it does seem a little cliche, it involves a variety of elements from previous FFs, mixing new and old, rebelling against an empire to saving the world. It does well to blend these elements together in a nicely told story that is sure to amaze you.
The characters of FF6 are of all sorts. Terra, Locke, Edgar, and much much more. They each bring something different to the battle field as each have different skills. Not to mention considering the huge variety of characters, the ability to pick and chose a really varied party is great. You also care a lot about the characters, viewing their past, their resolve, you can easily associate with each one and sympathize with their battle. This coupled with a great story, makes it another plus for FF6.
In terms of gameplay, FF6 is easily one of the most customizable. As you progress through the game, you gain the power of Espers. Espers provide a variety of abilities, such as HP increase, learning a variety of magic etc. This gives you the option of customizing your characters easily, want Terra to be a tank? No probs, get her to stack her HP. Want Locke to cast white magic? No probs, give him white magic abilities. Battles give you AP, which you gain in order to gain the skills. Also you can only equip one Esper per character, so you can't easily stack. The battle system has hardly changed, it still retains the old ATB system from FF4 and FF5.
Overall, FF6 is simply put one of the best FFs to date. From the beautiful story, to the loving characters, to the act in the Opera House. Every little thing of FF6 will charm you and honestly make you fall in love with it every step of the way.