The shades you choose should be based on what function or benefits your trying to accomplish by installing tint. In other words:
• For privacy or security, go with the dark or “limo” tint.
• For optimum visibility during the day and at night, choose light to medium tint. For a factory installed look, or a solid profile, choose medium for all windows.
You can also mix up the shades by installing light in the front two windows and dark on the back half. The shade you choose does not affect the price.