Horatio

               "Indeed, my lord, it followed hard upon." (I.2.26)
                 Hamlet is the only one brave enough to be honest, and that shines through as one of his virtues. This confession of the inappropriateness of the marriage of Gertrude and Claudius reveals his loyalty to Hamlet this early in the play. He is one of the only sympathizing character in this whole play.

                 "As I do live, my honour'd lord, 'tis true; and we did think it writ down in our duty to let you know of it. " (I.2.7)
                   Here again, we see that his loyalty lies with Hamlet. And he is pure and innocent enough to not plot and ponder whether or not he should reveal this ghost to the lord Hamlet. No, as a good friend he goes right to Hamlet, not fearing if this story will scare him, just knowing that it is the right thing to do.

                 "O my dear lord—" (III.2.38)
                  This is great. One can almost see him blushing and finish the sentence: "O my dear lord, I am just doing my duties as your servant." An aura of humility surrounds Hamlet and makes him one of those lovable characters. He apparently esteems Hamlet's complement with great worth, which makes him such a good servant.

                 "Never believe it. I am more an antique Roman than a Dane.Here's yet some liquor left" (V.2.79)
                   He would go down right next to his master without a second thought. To the very end, Horartio remains his loyalty to his prince, when everyone had turned to the new King. This last scene amplifies the golden heart of Horatio and his extreme servant-duty of dying for his kingdom.

                   "Now cracks a noble heart.—Good night, sweet prince,And flights of angels sing thee to thy rest!" (V.2.89)
                      He finally speaks his love for his Hamlet. It could have been conspicuously implied  before, but now that Hamlet is dead and cannot hear Horatio sees no need to hold back the words that have always been in his heart. It is right that Horatio be the only one left alive since his role in the whole plot was innocent and dutiful.