Sun Tek and Xpel from my findings have been the leaders. All of our cars are Xpel. The installer is really what makes the difference, so find him or her 1st, and then defer to the product that they use. "Today's" films are amazing. I have some cars that are 10+ years old, and you look at them and go ouch (I really need to change them), but recent ones, you just cant tell. As referenced, yellowing is not an issue, and Xpel even offers a 10 year warranty against it.