Big Otterbox Fan...
I had the Otterbox Defender for my IPhone 3G. I had a few other cases before that, and I found that the Otterbox case to be by far the best: it looks good, it provides good protection, it feels good in your hand, and fits easily into your pocket.
I think that the Commuter will be even better, giving you the protection of the Defender while fitting even better in your pocket, so its my new choice.