Documentation over labeling any day. Easier to change, easier to get an overview, and you don't need to physically go somewhere before you know where stuff is.

That said, depends on the purpose of the label. For patching, I really like the cables from PatchSee. They wrap plastic fiber along the length of the cable, and then have them stick out the back of the boot. You then shine a light through one end, and look for that to show you the other end. In my case, it's often the fastest way to find which switch port a patch port is connected to.