I've been using the screen protector that is built-in with the Otterbox Defender for my iPhone 4S for a year now. It has some scratches so I've been looking to buy a new screen protector (and remove the currently built-in one). I've used Zagg Invisible Shield for my iPod Touch a few years ago and I really liked it. I'm thinking of buying another one for my iPhone but if you guys have had any good experiences with other screen protectors, let me know.