Looking to tint my 2012 white s5, what percentage do You think i should choose. Thinking about either 15% or 5%

What are your thoughts ?

 

The darker that's legal, the better. I bought a red S5 the other day, and paid $550 for tinting. It's audi tinting with a 10 year warranty. It looks really good off the red I got. I like windows tinted so that nobody could look into your car.