I've only played IV, V and IX. I've imported VII, but haven't got round to playing it yet and will get VI when it is released.
I would say that despite all having pretty much the same battle system and style, IX can be seen as a departure for the series. It has a large emphasis on co-operative multiplayer and has much more of a focus on post-game side quests. I've put 85 hours into my copy and I've only scratched the surface of the game. Basically, get DQIX.








