I would prefer the iPhone 4 but with the metal mid-band and backpiece being made into one solid metal piece. Then have the phone open up by lifting off the LCD/digitizer like we saw with the 3G and 3Gs. 😀 Also, recess the camera lens.
That way we wouldn't see any back glass breaking and replacing the LCD would also be a hell of a lot quicker.
Then offer it in black and white and it will look kinda like the iPad 2 but with the iPhone 4 form factor and the color choice only affecting the digitizer. 🙂