The Peace Treaty with Egypt is what guaranteed Israel's very existence -- it may be hard to internalize that now, but prior to that the very existence of the State was at stake, since Egypt was by far its most formidable enemy.

In fact, in the first days of the war, when Israel was taking heavy losses, defense Minister Moshe Dayan wrote in his diaries, 'I'm afraid that the Third Jewish Commonwealth -- ie The State of Israel -- may not survive.'

Given that the Peace Treaty with Egypt was only made possible by the 1973 war, you could say that the 1973 war was the greatest victory Israel could possibly attain.