In the play Macbeth, Act 1, Scene 3, what is Macbeth's first reaction to the three witches through his words and actions?

Condescending superiority.  He uses the imperative tone, belittles their abilities "if you can," and scoffs at their identity, calling them "what" rather than "who."  After they do speak, he insults them personally for their mistaken visions--"imperfect speakers."  He dismisses their first vision as obvious "I know that I am Thane of Glamis" and further justifies his "ad hominim" attack by couching his superior knowledge of truth in a question that he already knows the answer to (the way a student might mock a teacher's error by posing the teacher's point in a question designed to expose the teacher's mistake and by contrast, the student's superior knowledge).  He then continues the questioning assault, daring them to answer.  When they leave, he wins--his "Would they had stay'd!" is the delight of the victor who wishes he could have messed with them some more.  But since they've left, he satisfies his lingering urge to gloat by teasing Banquo: yeah, right, as if Banquo's kids would ever be kings.

His first reaction shows he's a bully, and even a bully to his best friend--though he couches the cut to Banquo in a joke, as a bully will do.