Luffy has a lot of brilliant moments. No doubt about that. Helping Nami out once he learns the truth about Arlong and her motives, defeating Crocodile for the first time, his battle at Marineford, his final moments with Ace. Those are all great moments. However, my favourite Luffy moment is the scene in which he saves the Lapahn despite how much trouble the creature gave him beforehand. It just highlights his benevolence and really does convey how big his heart is.