Impressive claims - "MobiFolders 2 is the fastest file manager for iPad and that even with a very large amount of data. The start time on an iPad Air is less than 1 second regardless of the number of managed files."
Someone with an iPad Air can verify the claim.
Too many fetures to list, but does almost any as a 1) File Manager 2) PDF Viewer 3) File Viewer
A free file manager being released on 17 Sep in the form of iCloud Drive