A fanny pack for every trip!!! It is so comfortable and easy to access! Backpacks are scary as all your things are behind you and can be accessed by someone else.
And not to mention how many times I have experienced or witnessed a backpack wearer turn around and hit another guest(or me or my kids) because they forget the pack is back there!!! Also as mentioned you do not always need to take off the pack for rides! Found a few backpacks on rides that people forgot to grab at the end of the ride. My DH and I take turns wearing it. Don't care what anyone else thinks- it is perfect for getting around Disney!