I've got the Otterbox Commuter for nearly a year now and I'm very happy with it.
It already saved my I9000 several times, including drops against hard floors and asphalt. The phone survived and the case itself wasn't dented.
It is also gives a surprisingly good surface grip when placed face down.
I myself like the design, it is a little bulky but that's what you pay for protection.
Better looking the case-mate in my opinion.
Only cons I can think of is the included screen protector which is awkwardly cut shorter than the actual screen surface. I just replace it with a 1$ one from ebay.