Nagato, bcuz he didn't even have a family or clan in his youngest dayz, the only reason he lived as long as he did was bcuz Jiraiya took mercy on him, sure Itachi killed his clan, but he went through with it, so evidently he put up with it. And atleast Itachi did have a family until him and tobi killed them all, imagine if you were an orphan with just two of your closest friends at around 9 or 10 years of age, that's the freakin hard knock life, I'm pretty sure sometimes they struggled for food, whereas Itachi was pretty much grown by the time he was in his teen years, this is just my opinion though