The Straw Man argument or Malicious Misinterpretation
I think the most powerful fallacy - and most favored by the villains of the world for winning arguments - is the Straw Man argument, which I have renamed "Malicious Misinterpretation". It does not matter how sound your argument or how carefully stated to such debaters, they will hunt through your sentences, find the most outrageously stupid interpretation of your words and argue as if that was your meaning. You are endlessly having to say, in effect, "No, no, that is not what I am saying." This is a real talent and is practiced artfully by most debate-cheats. By refusing to get your point, they effectively short-circuit the debate. I notice it especially in the very liberal, who delight in the assumption that humans are generally so stupid that they need to be controlled. They are gifted at finding interpretations of every challenge to their beliefs which make those challenges sound absurd.