I use this, which allows me to use my existing case. No problems so far, but I've only had it a couple months.
Amazon.com: Aduro U-GRIP PLUS Universal Bike, Motorcycle, Handlebar, Roll Bar Mount for Smart Phones, Apple iPhone 6 / 6 Plus / 5 / 5S / 5C / 4 / 4S, Samsung Galaxy S3 / S4 / S5 / S6 / NOTE 2 / Note 3 / Note 4, Motorola Droid RAZR / MAXX, HTC EVO 4G,