I haven't seen Arrow yet, so I voted for Young Justice. It was the show that made DC animated series so good and make me remember the good series we had: Batman the Animated Series, Batman Beyond, Justice League, Superman, Static Shock, and Teen Titans.
The newer DC animated series for Batman wasn't surpassing its counterpart. We finally had something that isn't on Batman.
It's a shame that Young Justice was canceled due to low toy sales. I heard the staff blame the demographics because they felt the overwhelming female presence wasn't buying toys or DVDs. They should have rethink their marketing strategy for both genders. Young Justice had that spark which never could be drawn out for its fullest potential. I had Korra and Young Justice for cable's animated series' weekly watch. I loved YJ more than Korra because it was more realistic perception of teenagers and their problems, dealing with so many responsibilities.