The Quick answer: No one! The more involved answer: Morality oozes from the lines of Hamlet. While the foundation of the play is clearly revenge, it can certainly be seen as a lesson, not in how to revenge oneself upon his or her enemies, but on the downfalls that follow revenge. Hamlet’s world is turned upside down by his quest to revenge his father’s death by killing his murderer, Claudius. He finds himself trapped in indecision, unable to act. The actual revenge act, to kill, could be very simple but instead Hamlet spends his hundreds of lines (more lines in fact than any other Shakespearian character) deciding how best to act and not actually acting. Because Shakespeare views the act of revenge as simply amoral, he makes it almost impossible for his hero to accomplish. Instead Shakespeare sends Hamlet into a world of mental torment. He ponders his own death more heartily at times than the planned death of his uncle. In the end we see that revenge is more of a curse than the original crime that is being revenged.
Shakespeare conveys this truth in many ways, one of which is the estrangement of Hamlet from Ophelia. It isn’t until she has died that Hamlet is able to see what his quest has done to her, and then still he is unable to desist. In the end, when nearly all of the major characters of the play lay slain, Shakespeare has truly shown the reality of revenge. While it is true that Claudius is among the dead, Hamlet (and the reader) must know that the revenge is certainly not sweet. No one wins.