Otterbox Defender, Speck Pixelskin HD, Belkin Shield Eclipse.
Belkin: Worst of the 3; plastic is real hard and I'm afraid of breaking my iP4 everytime I get it out. Buttons are extremely stiff. Good protection though, but if I could sell it, I would.
Speck Pixelskin HD: Just had it yesterday, but it is already my favorite. It's slim, yet a good protection. The plastic is just stiff enough for protection but bends really well to remove your phone from it. Buttons are soft and that case screams sexayyyyyy.
Otterbox: Ok, first you got to know I have a real fascination about everything Special Ops, and when I first saw the Defender, I wanted that case. Cons: it is bulky. Real bulky, like I only put it on when I wear loose jeans or when I go in the woods/nature. Also because of its bulkiness, the home button loses 25% of its surface. Look at a pic and you will get whay I say. Pros? TONS. It is the best protection for your iphone, the buttons are soft and smooth, it gives a better grip on the phone than any other case, and it really is the most masculine case on the market.