I think Liberman and the phonies in Blue and White are the worst currently. Barak today is irrelevant. He's not going to join a coalition with Lieberman now that he is with the ultra Left Wing Meretz people in his new Democratic Union. The Left thinks he's an extreme nationalist but the Right knows the truth that Lieberman is an extreme Leftist who even wanted to give away parts of Pre-1967 Israel as a way to expel the land rather than the Arabs living there. Liberman doesn't understand that supporting religion is part of being a Right Winger in Israel. You can't call yourself a Right Winger and be against religious parties in a coalition.
If I was asking who were the worst of al time, I would have included Moshe Dayan and Shimon Peres. Moshe Dayan is probably the worst since he invited the Arabs back after they fled from Judea and Samaria and because he gave back the keys to The Temple Mount. Shimon Peres gave the Arabs land in Judea and Samaria. So all the problems stem from those animals.