I'm due for an upgrade from my iPad 2, and I'm leaning towards the Mini. As of right now, I expect to wait till early next year to purchase a new iPad and I think my deciding factor will be how bigger of a screen will the iPhone 6 get. I expect we will hear more solid rumors early next year on how big it will be.
Should the iPhone 6 get a 4.8 or 5 inch screen, I would lean towards the iPad 5. But if the iPhone 6 gets a minimal increase to 4.3 inches, I would get the mini.
Just saying but you won't know that by early next year most likely.