I liked the whole book. I LOVED the second Battle. I LOVED that Molly killed Bellatrix.
But my favorite line was way back at Grimmauld Place when Hermione says: "I've said all along that wizards would pay for how they treat house-elves. Well, Voldemort did... and so did Sirius."
Oh, and when Snape told Lily being Muggle-born didn't make any difference.