ALL people who hate Jews are dangerous, and it is difficult to know with certainty who is the most dangerous, because nobody knows the future with certainty.
However, the political Far Left [also known as the Radical Left or The Woke or The Socialists] are especially dangerous to Jews, because they dominate numerous powerful institutions, for example:
almost the entire news media, almost the entire Hollywood entertainment industry, almost all High-Tech & Social Media companies [except for Twitter, recently bought by Elon Musk], almost the entire educational system [especially colleges and universities], almost the entire Democratic Party, and many non-Orthodox synagogues and large churches and big non-profit organizations (including Amnesty International, the Rockefeller Brothers Fund, the Ford Foundation, and the New Israel Fund, Human Rights Watch, Oxfam, NGO Monitor), and many more.