I have used the Cropper Hopper Paper holders for a few years now. They are a great way to organize and hold your papers. You can see what you have and they don't get wrinkled. You don't have to thumb through the paper to see what you have. The divider tabs are great too. You can divide your patterned paper and that helps me a lot. These just sit very nicely on my shelves. I also have the 8 x 8 and 8 1/2 x 11 sizes. They are just perfect!
I have the 12x12 and 8.5x11 paper organizers, so I had to get the 8x8 to get the rest of my papers sorted. I really like this vertical storage. These are incredibly sturdy - I've had the 12x12 paper holder for years! I also really like that they're translucent, I can see all my papers at a glance!