I'd have to say Naruto.
My answer may slightly be biased due to the fact that Sasuke endlessly annoys me, but the thing is, Sasuke had people who cared and loved him. It's true that he suffered greatly and it's terrible how his beloved brother ends up killing his parents and his entire clan, but he always rants about how it hurts to lose bonds. But what about Naruto? Why doesn't he ever complain about how painful it is to never have bonds? To never understand how it felt to be loved, to never be held in your parents arms, to not have someone to laugh with? Naruto never had these experiences. He never felt that happiness Sasuke had as a child.
To be hated so much for an unknown reason. To be isolated and never know what happened to your own parents. It's like solitary confinement.
When Sasuke lost his clan, he lost his most important people. But the thing is, in my opinion, there were still people who were looking out for him, who so obviously cared about him. He was still loved. Naruto never even knew if anyone cared about him. Practically the whole village wanted him dead.
