Which Justice is the "right" Justice?

In the reading, there were two arguments presented on what justice is. The first argument by Glaucon is that people will do whatever is in their best interest which will usually come at the expense of someone else. Socrates argument is that people will do whatever is right regardless of if they benefit from it or not. For me it's hard to say that only one argument is correct since I see both sides. Speaking from personal experience (and I'm sure I'm not the only person that feels this way) a part of me always wants to do what is right or what is best for other people. To sacrifice what I really want for the happiness of everyone else, however part of me is still very selfish and doesn't care about if other people suffer because of an action or choice of mine. Where does one draw the line between what is just if what is "just" for the individual may not be "just" for the community? If I act in a way that is beneficial to me but not to someone else is what I'm doing just? It is what's right for me so if I don't do the action or what have you I would be acting in a way that is unjust to myself and is that better or worse than me doing something that is unjust to someone else? If we lived in an experimental "state of nature" I believe that Socrates' argument would fall flat because people would look out for their own interest only. I sincerely doubt that people would be concerned with if what they're doing is right/just if there is no one to tell them what they're doing is wrong/unjust, they would be more concerned with taking care of themselves at pretty much all costs.