When I first watched Home Alone as a kid, it scratched an itch for wish fulfillment in me. What kid doesn't want to have the run of the house and be unsupervised for a few days? What kid doesn't want to set up elaborate traps in said house to foil buffoon is would-be burglars? Home Alone delivers these fantasies in a big, entertaining, and satisfying way.
Watching it as an adult replaces the wish fulfillment with a deep nostalgia. And the performances across the board are fun and personal, when they need to be. Kevin's arc from being a whiny kid who "wishes his family away" to a strong, self-sufficient guardian of the house is so much fun to watch play out.
The sentimental way he comes to terms with his predicament and grows to miss and love his family is really sweet and compliments the holiday season setting of the movie very well. On the flip side, Catherine O'Hara's subplot of trying to get home to Kevin is really endearing and her frantic performance really makes you feel for the situation whole also keeping the movie grounded.
Finally, anytime I bring up Home Alone, I can't help but mention my headcanon that Kevin McCallister grows up to become Jigsaw from the Saw franchise because the traps he sets in Home Alone are pretty gruesome for an 8 year old.