In the Attack On Titan universe, it is imperative that humanity has capable warriors to defend against threats both foreign and domestic. This was partially why the three walls had been established, with a matching three different military branches to fulfill all duties necessary to ensure the country's survival.
Though it may be considered noble to enlist in the armed forces (scouts or otherwise), many of those who did shirked their responsibilities. By analyzing the actions of the nation's defenders, we can gauge who served their people well and who disgraced them—whether they intended to or not.
10 Disgrace: Ymir
Ymir was the guardian and love interest to Christa (who would later be known as Historia and the queen of the nation). Though her vigilance in protecting her may have been commendable, it did not excuse the actions she would take in consummating their bond.
As Reiner was being overwhelmed by titans (under the order of Eren), she would assist him against his foes, providing an invaluable service that he wouldn't soon forget. However, considering that her armored companion was an active enemy to the Scouts, this was effectively an act of treason.
9 Champion: Sasha
Sasha was one of the Scouts' most grounded and realistic members. Though she had initially struggled with weighing the survival of others to that of her own (since she lamented the refugees' encroaching presence on her land), the woman would nonetheless offer her service to her country.
Despite her occasion spurts of hedonistic gluttony, Sasha has demonstrated profound selflessness. It was proven through when she saved a young girl from a titan without ODM gear, heroically lunging toward her gigantic prey and gouging its eyes out by stabbing it with an arrowhead.
8 Disgrace: Kitz Woermann
Kitz Woermann was the captain of the Garrison's 1st Division Elite Forces. While this might entail prestige to his office, he has done nothing to warrant it—oftentimes, debilitating his countrymen more than aiding them.
After discovering that Eren was a titan, he confronted him with belligerence and hostility, ordering his soldiers to open fire. Should his hysteria have yielded results, it would have deprived the Scouts of their greatest asset, squandered the Coordinate, and doomed everyone behind the walls to an excruciating death at the hand of the titans. Fortunately, Commander Pyxis intervened before he could finish Yeager off.
7 Champion: Hange
Hange was an intelligent woman who led the Scouts to many victories and was able to think rationally under dire circumstances. More importantly, her brilliantly scientific mind allowed her to create inventions that would prove invaluable to the nation's efforts in thwarting the titans.
Aside from the automated killing contraption she had mounted along the walls, her experiments were also responsible for helping Eren mend what breaches were made through his crystallized titan body. Therefore, the restoration of Shiganshina can partially be attributed to Hange's genius. Further, she also helps the Scouts on the frontlines when her services are required.
6 Disgrace: Kenny Ackermann
Kenny Ackermann was the uncle of Levi and one of the interior police's cruel leaders. He hunted his former pupil viciously upon the request of Rod Reiss and would defend his master with equal fervor once Eren had been captured.
Bizarrely, he would also abandon the royals, attempting to coax Eren into fighting Historia. The Ripper's indecision resulted in the needless death of his own people, and he wasted his opportunity to kill Rod before he became a massive monster larger than even the Colossal Titan.
5 Champion: Erwin
Erwin was the gallant leader of the Scouts and a military genius. It was through his design that the corruption within the Interior was unable to execute Eren and subsequently crippled the nation of their greatest utility. Further, he led the charge against the Beast Titan along with his compatriots, suffering what would become a fatal injury for his courage.
Though Erwin is not perfect—having admitted that he's willing to compromise humanity's survival if he isn't there to see it—his selflessness was nonetheless an example to those beneath his station.
4 Disgrace: Jean
Unlike many of the other characters that disgrace their nation, Jean actively tries his best to serve the Scouts. However, most of his actions have been unproductive at best and possibly even sabotaging.
He initially wanted to join the interior police for an easier life, constantly berating and fighting with Eren (sometimes even physically). These shortcomings pale in comparison to his most grievous mistake; coaxing Hange into sparing Reiner and therefore enabling the Armored Titan's escape. It was an error that halved the success of their costly mission to retake the outer wall.
3 Champion: Armin
Armin was the childhood friend of Mikasa and Eren, a natural genius whose intellect was respected by Erwin himself. His brilliant mind had produced many viable answers to some of the Scouts' worst problems, including the deduction of Annie's identity and where Reiner was hiding during the reclamation of Shiganshina.
Further, he was able to balance his wits with his will. In order to distract the Colossal Titan, he allowed his entire body to be incinerated to blackened cinders even if it meant he would never look upon the sea. Fortunately, he was saved before such a cruel fate befell him.
2 Disgrace: Reiner
Reiner was a former member of the Scouts who helped Eren with his training. He was powerful enough to lift a titan over his back and throw it out of a building in his default form, demonstrating his raw physical strength.
Unfortunately, he was revealed to have been the Armored Titan and responsible for untold deaths and suffering—indirectly including the culling mission that took place in order to make the country's population crisis manageable. Though Reiner was an active traitor to his people, he occasionally showed glimpses of remorse for his actions.
1 Champion: Levi Ackermann
Levi Ackermann was easily the most talented Scout of the entire regiment and a decorated war hero. Surviving a childhood of hardship and abuse, his skills became recognized by both his comrades and enemies in an astonishingly short time.
Possessing the willpower to do what is necessary for survival (such as psychologically torturing his enemies) and the skill to match, he is the image of a perfect soldier. Accordingly, Levi was perhaps the only man alive capable of bringing down the Beast Titan on his own.