7 is my favourite game of all time. X is probably my second. XIII is the best Final Fantasy since X by a damn long shot. I don't really count X-2 and XII when talking about Final Fantasy as they were atrocious.
The story is very good, and whilst you do have a main character, when the game opens up you can choose your party with or without her in it. (although Lightening is the most well rounded and awesome, not choosing her is just silly
When Sentinels become quite necessary(as soon as the hand holding is over with) the battle system really shines. It's far more strategic than previous FF's. And it can really kick your arse for making a mistake.
You don't get 'random' battle anymore either which is another huge negative to non FF fans. Instead you see the enemies and whilst some you cannot avoid, others you can if you're in a rush.
And the fact that after you beat the main story (don't forget to watch the credits and save afterwards) there is a TON to do on Gran Pulse.