In The Great Gatsby, in the end, does Daisy choose Tom or Gatsby? Why?

The Great Gatsby makes clear that Daisy has chosen Tom over Gatsby and would have done so even had Gatsby lived.  In the confrontation in Chapter VII, in which Gatsby tells Tom that Daisy has never loved Tom, that she loves Gatsby, Daisy first tries to stop him from doing so. Once he does, Tom responds by saying that even though he drifts from time to time, he loves Daisy and Daisy loves him. Daisy regards Tom with contempt, but then says she loved both Tom and Gatsby. There is a point at which she seems as though she is going to leave Tom. Gatsby tells Tom, "'She's leaving you'" (Fitzgerald 140),  Tom responds that this is "'nonsense'" (140), and Daisy says "'I am, though'" (140). She want to leave immediately, not able to stand the conflict.  But then Tom attacks, explaining the sources of Gatsby's money, in bed with organized crime, selling grain alcohol, and now some business venture so dangerous that Tom's sources won't say what it is. Gatsby gets a look on his face as though he had "'killed a man'" (142), and begins to defend himself to her, denying all.  But Nick says Gatsby's was now a "dead dream" (142), slipping away with the afternoon.  Even after she is saved by Gatsby's chivalry from a hit-and-run and manslaughter charge, Daisy remains with Tom, and they leave town well before Gatsby's body is discovered.  Gatsby dies waiting for a call that was never going to come. 

Daisy is a child of wealth and privilege, spoiled, careless, and shallow. Her world consists of people who are like her, and Tom is a part of that world.  Her sole foray into a different world in her youth, her fling with Gatsby, is not enough to make her leave that world.  Gatsby is a self-made man, unpolished, not having made any fortunes yet when first they meet.  He is a "nobody" socially.  Daisy's family intervenes somehow to stop her from seeing him off overseas, but once the war is over and she is a debutante, she is old enough to make her own decisions and chooses to marry Tom Buchanan.  When Gatsby returns, he is still a "nobody," and even worse, apparently a criminal.  She cannot see that Gatsby's love for her, his constant heart, and his utter decency as a human being (criminal activity notwithstanding) far outshine Tom's brutality, stupidity, and infidelity.  She is really not worthy of Gatsby's love, but she is worthy of Tom's, I suppose. And so for her, the choice is clear.