As a kid I always liked the arena scene in Attack of the Clones for some reason. I also like Finn and Poe's escape in Force Awakens, and the cantina scene in New Hope is such a classic.
Ever since I was a kid, and even now, my favourite scene is from Revenge of the Sith where Obi-wan stands over Anakin on Mustafar. It's such an emotional scene for me.