Any little kid that's overwhelmed with joy when they first meet the likes of Spider-Man,SpongeBob SquarePants, or a Minion. Or going through "The Wizarding World of Harry Potter" or the Despicable Me ride.
The ending of E.T. Adventure, with the titular character wishing you farewell (and actually saying your name!)
If you're walking through the exit hallways at the right time you'll hear "I'll be right here..."
There's also the ending of Despicable Me: Minion Mayhem, where Gru saves the girls, reveals to the trio his 1st Anniversary gift to them and happily declares how much he loves them.
Doc Brown (gleefully): You did it! Not only did you catch Biff and save the universe, but you proved that my latest invention is a success! Go forth time travelers, and remember the future is what you make it!
The Universal 100th show, which is essentially a giant and lovingly-crafted homage to the company's legacy of films. It's especially moving to any big film fan or historian.