Documents is the perfect companion to other apps that I use, including PDF Converter, Dropbox and iCloud. Unlike the Windows equivalent (Drawboard PDF), highlighting follows the text flawlessly with the Apple Pencil and notes (both typed and written) display well. The app also allows multiple tabs and even a mode for searching for articles and items online to save as files to import back into the app; a must for researching for a paper.
The interface is a little cluttered, but outside of Notabilitys handwriting and recording functions Documents is tied for first place regarding must-have apps for an iPad Pro to finish college or use for ones work.
Wolf-coyote about Documents: File Manager & Docs, v5.7.8