Well as far as the Xbox 360 is concerned.
Lost Odyssey perhaps has the best story, and character development this generation for the genre. Most of the key players have rich deep stories, and it is both poignant and philosophical. With commentaries on immigration, solitary confinement, pollution, and corruption. The game has a robust over world, and a modest party size. There is enough to play around with character wise, and a lot of challenging side quest boss battles. Easily a hundred hours if you are of a mind to do everything.
Blue Dragon has a truly massive over world, and a large amount of physical real estate. It will take you close to two hundred hours to do it all, and you probably still won't be done leveling up. It takes between thirty to forty hours of pure exploitation of the leveling system just to max out your characters, and I am talking about running a macro, and rubber banding your controller. The story is sadly on the weak side as it is predictable, and the total number of playable characters is on the small side.
Infinite Undiscovery is actually almost overkill when it comes to available party members, character building, and inventory management. If you like having a lot of choices, and love micro management this game is for you, but it isn't really mandatory. This is a action role playing game, and you can get by with the minimum amount of real effort. It can be rewarding, but if you just want to bull rush the game you can get through it in about forty hours. The story is just a bit above average, and character development is on the weak side. However the world is pretty big. There isn't a over world so everywhere is playable real estate.
Anyway there is three hundred plus hours of role playing goodness there for you.







