Love my CapsuleRebel. The fit around the phone is really snug (kept sand out at the beach!), and the case does a great job at protecting from drops (I have a nasty habit of putting my phone on my lap in the car or while in a restaurant, forgetting about it, then suddenly standing up only to hear the horrifying sound of my phone clattering to the ground/parking lot/concrete). Happy to report that my phone as not a scratch on it. The inner layer of softer polymer seems to be very efficient at absorbing impacts while maintaining its original shape and subtle sponginess. I don't mind the spine because I rarely use my phone while its laying flat on a table. I find the case to be ergonomic when holding the phone in landscape mode.
A friend of mine bought a Commuter before she saw my case, and now she says she regrets it. The silicon around the edges allows dust to get between it and the phone, it attracts lint, and gets loose when it heats up (from being held, sunlight exposure at the pool, long Angry Birds sessions, etc). She just sticks it in her purse, but I'd imagine that the silicon would snag on your pocket if you kept it in your jeans. The Rebel on the other hand is very pocket friendly. With all that said against the Commuter, from what I've seen it affords her similar drop protection to my Rebel (we both dropped are phones off of a bar onto a restaurant's floor within minutes of each other. Was not planned).
I just don't like silicon cases, because they all seem to have the same problem due to the properties of the material itself. IDK, if the port covers on the Commuter will weaken and tear with time like I've experienced with the Defender. The Commuter is also thinner than I expected it to be. Its not brick-esque like the Defender, sporting dimensions that are much more in line with the Rebel. As far as looks go, I'd have to go with the Rebel. I find OBs to be bland and ugly, but I realize the Rebel is a little too "Alien" or "Batman" for some people's tastes (my friends call it my batphone). To each their own.
I think in the end you'll enjoy either case and the protection they offer. If you're the type that likes to use their phone while it's lying flat on a table, go with the Commuter. Otherwise, the Rebel is a sick case.