I prefer 5% all around... but that is not practical for most folks...
35% on sides and rear looks ok, gives a decent amount of filtration and darkness in the car, and doesn't get me tickets or hassled. I would rather of had 20% but wasn't practical for me. (And Pinnacle didn't have 30%)
I think 25% if legal in your state would still let you see at night well enough not to be an issue, and look great!