Ares is often portrayed as a villain for his love of war regardless of side and, in the opinions of many, lack of morals and rules of engagement. In a way though, does Ares instead have a brutal honesty Thor and Hercules refuse to accept?
In Hercules: Agents of Chaos, Ares stated it was his divine duty to interfere in mankind's affairs and spread war. In Incredible Hercules, Ares pointed out how war makes nations into empires and men into heroes. In War Machine, Ares claimed one reason men like him and Rhodes go to war is it provides them with the enemies they need to be heroes instead of monsters. In his Psych War Profile at Marvel.com, Ares claimed his villainy was largely a matter of perspective. The side he fights for considers him a hero and the side he fights against would consider him a villain.
Would you say there is a certain brutal honesty to Ares? Think about things from his viewpoint. Zeus claimed to be the upholder of morals and law. Yet look at his treatment of mortals, mistresses, and what he did to Metis making him little different from Kronos. Time and again throughout history Ares sees mortals fighting. Each side claims to be in the right and for a just cause. Time and again he sees them engage in the same tactics as the ones they villainize. Whatever cause they fight for fades away and a new one comes up. Throughout history long periods of warfare are only stopped when one power conquers the others and many benefits have come from empire building. Since to him all sides use the same tactics and eventually fade away no one side has a strong claim to moral superiority over the others so why should he favor one side or the other?
Now look at Hercules and Thor. In ancient times, Hercules was as violent as Ares and prone to fits of madness. His targets were usually acceptable targets like monsters, but not always. Hercules was known to sack entire cities or slay entire families due to a king provoking him. Yet in modern times he is remembered as the greatest of Greek heroes. He may have mellowed some and is nowadays more of a brawler, but still without violence of some kind he is bored out of his mind.
Thor is a great warrior who fights in defense of Asgard, but how do you think the frost giants see him? In the older tales, Thor would often go hunting giants in Jotunheim. Would not he then be a villain to the giants? What would Thor do if there were no giants or trolls to fight? It has been implied one reason Odin kept them around was to give someone his soldiers to fight. Hardly the peaceful utopia many people think society should aspire to.