The following is based on my observations. I use my devices and I abuse my devices. If a case is "waterproof" ie: IP-68, then I trust that the claim is true and use the device / case as it is advertised.
I have been a fan of LifeProof
(an OtterBox Company). I got my wife the original Fre case, it was great, but fell apart. The big problem with the Fre, was that it had a built in screen protector. After much wear and tear, the Fre fell apart. I then got her a Nuud case. It is great. The Nudd does not have a screen cover, as the gasket is around the screen. It has held up much better. So I bought a Nuud case for my iPad mini. I also got the life preserver and the Cover+Stand. The whole package is great. I had it in Avalanche Ranch Hot Springs yesterday and on Carbondale to West bank family float trip. I took pictures, streamed music to an EcoXBT
waterproof / BlueTooth speaker and took a few reservations for the oxygen business as I sat in the hot springs and floated down the river.
My only beef with LifeProof is the yellow charging port door gasket. It falls out (has happened to 2 cases) You then have to send LifeProof an RMA with the serial numbers from the inside of the case (1 on the front part and another of the back part inside the case) Life Proof will then ship you a whole new case and a container and shipping label to send back the old one. In these cases, I did not need a whole case, only the yellow gasket. They would not ship me a gasket without the serial numbers and then sent a whole case. I find that this is wasteful and unnecessary. At some point, I might need to warranty the whole case, but I don't want them to think I am abusing their generous warranty process when I only needed a $.50 gasket. I told them I would happily pay, but they refused.
I also have a Seidio Obex
case for my Samsung Galaxy S4. I have used this case for the last 10 months. It is SOLID. in and out of the water. I had a skateboard accident and my phone bounced 40 ft across the street and still works. Had a few scuff marks, but nothing that compromised the case. Very impressed with it.