I have tried best skins ever and invisible shield. Currently I have bse on front and invisible shield on back. I have invisible shield on back because it is thinner so it doesn't get messed up when I put my incase snap on.
I would say bse is more clear than invisible shield and has less orange peel. It feels more slick than IS which is good. IS also has these weird rainbow lines when looking from certain angles when you view anything with white backgrounds on the iPhone.
Overall Best skins ever has more precise fitment, is cheaper, same material, a bit thicker, excellent clarity, and their customer service rocks.
Not trying to bash IS, I still think they're great. They also have lifetime replacements which is awesome.
For the screen best skins ever wins IMO.