I had a 13" incase with the velcro flap over the pockets for my white 13" macbook which I loved for the 4 or so months that I had it. I just got a 15" macbook pro and I quickly bought the 15" version with the zipper over the pockets and, again, I love it.
The inside is nice and plush and there's the perfect amount of padding to offer an assurance of protection without the annoyance of bulk. I was able to buy it in black for both versions which pleases my taste in aesthetic, too.
The version with the velcro flap, I believe it's the "plus" version, is nice because you can somewhat over-load the pockets on the case to bring with extra things that you might not normally pack. With the version with the zipper over the pockets I am still able to comfortably get my charger with the extension cord in and have the other entire pocket open for my ipod touch or a camera, or even both. However, it does seem a little snug every now and then when I remove my charger from the case because the zipper doesn't allow a large opening for taking stuff out, which the flap version did allow.
Either way, I've owned a number of cases. For portfolio style with shoulder straps I would strongly recommend the incase cases based on price, look, function, and durability.
For a sleeve I would recommend the Tom Bihn velcro-shutting sleeves. They are quite protective, look good, and are reasonably affordable.
