My favorite I'm gonna hafta say is more of a collection of souvenirs combined into one. I don't remember when, maybe about 15 years ago, my family acquired two free DisneyQuest backpacks as part of some promotion. We had to go there, our very first time to DQ, to claim them. Well, I never really used the bag, but time went on. I had a daughter of my own, and earlier this year was her very first trip to the parks. Since she was two, I knew that I would need to carry all sorts of crazy random things. Snacks, drinks, diapers, change of clothes, recycled toys (she loved my retro Fantasmic Maleficent dragon fiber optic toy), princess dress (even though not needed) and various other random things that made the trip extra magical (and more affordable).
The bag is now decorated with various things from all my visits, and I can't wait to go back to show them all off to other park goers.