I have the OEM Verizon Case, the Snap On Gel Cover. It works pretty well.
I like how it is rubbery so it doesn't slip on surfaces, although that can get annoying when taking it in/out your pant pockets.
The only REAL bad thing about it is that at the corner on the top piece where it connects to the screen, the plastic seems to protrude a little. This rubs against the nice glossy surface on the right side of the keyboard, and eventually it actually started to scratch some of the paint off. Not a big deal, but I am a perfectionist and notice these things.
To fix this issue I used sand paper on the case to file down the plastic. Seems to be better now.
I am looking at the Otter Box case as well. The fact that it works with the extended battery is especially appealing to me.
Oh and if you need another reviewer Joelmic, I'm your man. I'm even fluent in Spanish if you're looking to target broader a demographic spectrum xD.
EDIT 2:
So the case scratching into the nice polished surface on the right and left of the keyboard REALLY got to me (again, I'm an over analytical perfectionist). I really got down with some 100 grit sand paper and sanded away at the corner fittings. I took about 2/3 off the plastic off, so it still remains strong enough to support the case on the phone, but no longer contacts the polished surface.
To fix the scratches, I got some Pledge polish (not the spray stuff) and polished the nice surface to perfection. Now I am a happy camper.
Another feature I forgot to mention is that the case fits perfectly into the car dock.
Now I can say that I am truly happy with this case, and will likely not be purchasing a Otter Box unless I'm missing some outstanding feature.