The parallax wallpaper in iOS 7 is one of people's biggest annoyances with the operating system, but that doesn't mean everyone hates it. If you enjoy the effect where the wallpaper moves around a little behind the icons, CNET put together a guide on making the perfect wallpaper that actually works properly with parallax.
Parallax is meant to show depth on the screen, but you need to pick a wallpaper that actually shows off that depth. CNET explains what works best:
Picking a wallpaper that's a single colour, with no depth or texture to it, will all but eliminate the motion effect. But picking a photo with depth to it and that's the proper size will create a true motion effect.
Likewise, you also need to pick a wallpaper that's a little bigger (about 200 pixels on each side) than the screen size already on your device. Head over to CNET for the full guide.