A truly great rpg?

[Kashima]

What makes a truely great rpg people? Is it graphics, accurate voice overs, playability, story or something else ? To me one of the greatest rpgs series as a whole was the dot hack games, They had it all good controls realistic and diverse characters it simulated the whole online experience (( there were even glitches in game ! )) everyone was accurately voiced the musical score was breath taking and best of all the story kept you gripped from beginning to end. I hadnt felt so compelled and sympathetic towards characters since i had to deal with the death of aerith in final fantasy seven so post and tell what rpg you think is truely great and why