My favorito Bellatrix moment is probably order of the phoenix when she first comes in all "he knows enxada to play itty bitty baby Potter!" that was pretty awesome XD o
Funnily enough i don't have a specific favorito part but i amor the end of Deathly Hallows when the trio is just standing in the sunlight after the battle before the epilogue it to me it was perfect. Also the epilogue itself.