At one point this would have been an easy question answered by a few Disney movies. But now, I have absolutely no idea. In terms of in-theaters, ET takes the cake with three times - once for the special edition, twice for separate revival screenings. The only Star Wars tape I wore out was IV, so I guess that should go on the list too.
It's really easy to confuse "most viewed" with "favorite" unless one of your most viewed is something you've seen recently again.