Honestly...
Puss in Boots: The Last Wish.
Just an absolutely mesmerizing movie filled with impactful themes and amazing character growth. Visually gorgeous, paced perfectly, a great soundtrack with an unforgettable musical number, it feels so magical from start to finish and is really just all around perfect.
My personal favorite will always be Guardians of the Galaxy Vol. 3 (with Vol. 2 a close runner-up) because of all the feelings it made me feel and also being a masterpiece in its own right, but if I'm trying to be cold and objective, there are some minor flaws in it, and some bigger flaws that aren't so much the film's own fault but rather a consequence of having to fit into the larger Marvel universe stuff.
And sure, if I were to go for a more "typical cinephile" answer, I can always say Alien. That's another perfect movie I love a lot.
