The strongest arguments against free will are not scientific arguments but simple, a priori, deductive arguments, though like all arguments against free will, they are not persuasive, because belief in free will is not based on reason but simply a "feeling" that one has free will, even if no one can even give a coherent definition of what free will or "choices" are.
If we had absolute freedom, human behaviour would be completely unpredictable, but no one is claiming we have absolute freedom, devoid of any influences.
You also won't get anywhere on an argument that relies upon the truth of determinism, because free will libertarians are indeterminists. They believe that the condition "I could have done otherwise" is what gives us free will. They do not realise that being able to do otherwise actually means we are *not* in control of our actions precisely *because* we might have done otherwise.
I've written about ten or so different arguments against free will here, usually several paragraphs long, but people tend to just downvote me without even leaving a comment, so I'll stop here.