Go for tints by Solar Screen.
Im using their 10% tints on all glasses in my civic X for last 3 years.
A simple example to show that they are really effective is when you are travelling towards the sun which is shining through the windshield directly on your laps and lower torso, with these tints I no longer feel my clothes getting hot even in peak June sun.
Whereas before these my laps would start to burn.
I think they do full car in around 20k. Totally worth it.
Also I have a colleague's car with 3m tints. Have not felt any difference between the two.