I prefer Aristotle:
For every intellect chooses what is best for itself, and the decent man obeys his intellect. Now it is true also, concerning the upright man, that he performs many actions for the sake of his friends and his country, and if necessary dies for them. For he will discard both wealth and honours and in general the goods people fight over, gaining the fine for himself; for he would prefer a short time of intense pleasure to a long mild one, and a year of fine living to many years of living at random, and a single fine and great action to many slight ones. Now this like as not results for those who die for others; indeed they choose a great fine thing for themselves.
For a man to take something from his neighbour and to profit by his neighbors loss is more contrary to nature than is death or poverty or pain or anything else that can affect either our person or our property. … If a man wrongs his neighbour to gain some advantage for himself he must either imagine that he is not acting in defiance of nature or he must believe that death, poverty, pain, or even the loss of children, kinsmen, or friends, is more to be shunned than an act of injustice against another. … If he believes that, while such a course should be avoided, the other alternatives are much worse namely, death, poverty, pain he is mistaken in thinking that any ills affecting either his person or his property are more serious than those affecting his soul.
Every living thing has an initial attachment to its own constitution; but a human beings constitution is a rational one, and so a human beings attachment is to himself not qua living being but qua rational being. For he is dear to himself in respect of what makes him human.
(Rand, of course, situates herself squarely on both sides of this issue.)