Though i love both, i'm going to go with Under the Red Hood. Partly due to the fact that it pays homage to the death of the Jason Todd-era Robin, Neil Patrick Harris is PERFECT for the voice of Nightwing and John DiMaggio runs Mark Hamill a close second as Mister J.
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"I've seen things you people wouldn't believe: Attack ships on fire off the shoulder of Orion; I've watched c-beams glitter in the dark near the Tannhauser Gate. All those moments will be lost in time; like tears in rain. Time to die." Roy Batty