100% colour customization, add camo designs, shapes, figures. Made your own custom paint job on your spartan or elite. Add in odd bits as well you can add to your armor such as knifes, pistol holders, grenade belts, ammo pockets.
Make it so you can have a character that has a high chance of not bumping into someone with the same design on it.
Hell Id make a pink heart covered spartan just for the laughs