Juliet's death was the most painful for Jack even more painful than losing his father. You tell in this scene that Jack is actually in state of denial about what's happened to her. Not only it was emotionally painful but it was actually physically painful for him to lose her. It's like Jack lost his other half.
![Lost - The final scene [6x18 - The End Part 2]](/img/n.gif)
Juliet's death was the most painful for Jack even more painful than losing his father. You tell in this scene that Jack is actually in state of denial about what's happened to her. Not only it was emotionally painful but it was actually physically painful for him to lose her. It's like Jack lost his other half.
Jack deserved this one for sure.