Laertes is decisive, confident, and a strong leader. Hamlet is indecisive, self-conscious, and unable to lead. Hamlet wavers - he wants revenge desparately, but he is too scared to follow through. This is seen in the "To Be or Not to Be" speech in Act III, scene i, where Hamlet specifically mentions his fear of taking action. Also, in Act III, scene iii, Hamlet has a clear chance to kill Claudius when Claudius is alone, but he is unable to.
After Polonius' death, however, Laertes barges in ready to take action. He challenges Claudius to his face, rather than trying to trap him in a confession like Hamlet does, and then challenges Hamlet to his face. In all his actions, Laertes is more upfront. He is a good leader in Act I, scene iii, when he shows responsibility in his speech to Ophelia, cautioning her with specifics and calling upon her duty to follow his direction.
Laertes is a steadier character overall, and this gives him an edge over Hamlet.
Laertes is more admirable than Hamlet because, while Hamlet is indecisive about following through on the promise to his father's ghost to seek revenge against Claudius, Laertes is quick to action. When Laertes finds out about his father's death at the hands of Hamlet in Act 4, sc. 5, he rallies supporters and threatens to harm Claudius because Claudius hasn't done anything to punish Hamlet. Later, in Act 5, sc. 1, when Laertes sees Hamlet for the first time since both his father and sister died, he attacks Hamlet. Throughout the play, one of the central problems is Hamlet's inactivity. Hamlet is even frustrated with himself for his inactivity, which becomes especially apparent in Act 4, sc. 4, when Hamlet discovers that Fortinbras is willing to risk the lives of many of his soldiers in order to reclaim a small, insequential piece of land. Laertes is never slow to action and that makes him, at times, more admirable than Hamlet. Another time that Laertes is shown in a positive light, though Hamlet is also shown positively in this scene, is in the last scene of the play when Laertes says, about the prospect of striking Hamlet with the poisoned sword, "And yet it is almost against my conscience." This tells us that Laertes is beginning to see that Hamlet alone may not be the cause of the deaths of Polonius and Ophelia.