Hawkboy avenging his family's death by killing Lex Luthor. After all the horror and suffering he caused, he finally gets his comeuppance. Also a moment of heartwarming, albeit a warped one, as Batman gave the kid the opportunity out of sympathy.
By the same token, Brainiac's utter destruction at the hands of Supergirl and the Kandorians.
Superman saving the planet and helping to usher in a new tomorrow for it.