Defender is more shock absorbent by far. The Otterbox has a lot more silicone on it.
The Kraken has this thin silicone that stretches out. The hard plastic has the nice matte/rubbery finish. It feels thinner than the Defender and more solid due to the fact it has a lot less silicone. My screen protector on the Kraken watermarked though while the Defender didn't.
The Kraken just feels cheap and the silicone on mine stretch in 2 days of pulling it in and out of my pocket. The clip is functional and pretty cool actually, but I hate clips/holsters so it isn't for me.
The Defender provides a lot more protection except for the fact that the Kraken has fewer overall "holes". The only thing uncovered is the earhole for the earpiece. Everything else has some form of cover on it. With this in mind it is probably more water resistant though I would submerge either since the plastic pieces don't fully seal.