I went with 10% Llumar ATR film and love it. It is very difficult to see inside but not too dark at night. (as long as you are used to tinted windows)
One important thing to note on the factor tint. GM has always used a grey tint that matches llumar exactly on other vehicles. On the H2 the factory tint (back and moonroof) have a purple tint. I had not noticed it until I put on the Llumar tint. The difference is barely noticeable but if you are a perfectionist this will bug you slightly.
