The difficulty with this question is that it is based on personal opinion rather than any sort of objective criteria. Few of the characters are admirable without qualification. Hamlet is duplicitous, cruel to Ophelia, and somewhat self-centered. Ophelia has the wonderful flower speech, but otherwise seems to lack intelligence and independence. Fortinbras is intended as a purely admirable character but has a fairly limited role in the drama.
My own personal favorite, in part influenced by Patrick Stewart's wonderful 1980 film performance, is Claudius. Even though he is intended as a villain, he is a complex and intelligent character, with a great deal of moral awareness (and awareness of his own failings). He is charming and eloquent, and acts in a rational fashion. It's true that he killed his own brother and tried to kill his nephew, and is rather unscrupulous, but he also strikes me as the only character in the play with whom one might actually enjoy socializing. Assuming he didn't poison you, he'd be an utterly charming dinner companion.