I'm in the market for a 15.4" macbook pro, and I'm deciding which of these two to get. I want something that will usually sit in a backpack, BUT if need be can be carried on its own. I'm having a ton of trouble deciding, but by and large I've narrowed it down to one of these two (unless someone can really convince me otherwise). My question is which should I get? How do they compare in space, protection, size, ease of use, craftsmanship, etc? Is one better for certain situations over the other? any other comments about these two products?