It's a big decision between PixelSkin HD and SwitchEasy Tones for me.
Apparently both cases have had early design problems. Both companies claim they've ironed out the problems. SwitchEasy Tones has a 2 year warranty. Just take a photo of your broken case and they will ship a new one.
I'm leaning toward the Tones case...
I got tones before pixelskin. The former is slimmer but it's harder to get the phone out. It also gets stained fairly easily. But I'm most annoyed with the hard back... It makes the vibration louder.