ACB Da Vinci Disappearance or Black Ops Escalation Map Pack?

I borrowed Assassin's Creed Brotherhood from my cousin and I probably won't have to give it back until like early July. Should I buy the Da Vinci Disappearance DLC for AC Brotherhood, or buy the Escalation map pack. I have been playing a lot of Assassin's lately and its my absolute favorite series of games. I haven't played CoD in a long while now but I wanted to play the new zombies map (the only real reason I would buy the Map pack) and I was wondering which of the two to buy. Any suggestions?