Speck Presidio Grip
One of the most popular cases you see whenever you leave the house is Speck. They're very popular and sold at nearly all retail and carrier stores.
The Speck Presidio Grip features a great design that's very rugged and guaranteed to keep your phone safe from drops up to 10 feet. They have a military-grade rating thanks to a strong dual-layer design.
Speck uses a soft TPU gel case on the inside and a hard polycarbonate plastic on the outside. However, that soft TPU leaks through cracks and slits in the plastic, making it extremely grippy so you'll never drop your phone. It makes it easier to hold and use and keeps it safe. They come in a slew of colors, too.