I would agree with CSS -- the Holocaust was reprehensible and horrible and despicable, true. The Armenian genocide was also despicable, as was Mao's Cultural Revolution and Stalin's pogroms and Pol Pot's plans and the Rwanda genocide and the Sudanese genocide. These are despicable because they were not some ancient or random act but well thought out murders (maybe not the Rwanda). Why does the holocaust stick out more? Well, I hate to say this but it's because it happened to Westerners -- the other acts happened to non-Westerners
And since it happened to folks like us, that's why we remember it more. In the far-east they do not think much about the Holocaust, they know about Mao's murders and Pol Pot's genocide.