I used to automatically go 20% because I wanted it to be dark. This time, I wanted something a bit different by not totally blacking things out and I got the 35% and its perfect for me. Its defintely tinted but you can still see through the car a bit which is what I was looking for. Ultimately its like the color choice, personal for everyone.
2014 328d MSport
2013 F30 Activehybrid3 MSport (Gone)
2012 F30 328i Sportline (Gone)