I've used both the Tucano Second Skin and the Incase Neoprene Sleeve, and I have to say I'm a fan of the Incase. Mind you, they were purchased for a Unibody MacBook (so they fit a little bit loose since it's thinner than a Polycarbonate one), but I found that the Incase fits snugger than the Tucano. Also, I'm a big fan of the fleece interior of the Incase. On the other hand, the Tucano has a lip on the inside to help protect from accidental scratches from the zipper. I personally like the look and feel of the Incase over the Tucano so I will recommend it over the other.
As for hard cases, I don't believe it's necessary to have one if you have a good sleeve (depending on how careful you are while using your MB), but if you do go with one I suggest Incase. I've tried both the Speck and Incase hard cases for my MBP, and the Incase felt much more durable, less brittle and more appealing to the touch and eyes.