We use these all the time for storing paperwork that needs to be kept for many years in our storage space. The boxes are very sturdy and stack well for this use.
Got these to move books to my new house -- they're just the right size so that I can't overpack them -- but have also found many other uses. Good for storing things I might want to get at easily; removable lid gives me ready access and then I can reclose the box (no need to tape or re-tape). Finally realized I could use these for their original purpose to move my work files!
These are the best moving boxes. Have used for both business and home from books to dishes. So easy to maneuver pack stack and store. And the best part is that after they store flat for use again.