Wu Zixu in the Autumn and Spring period defected from Chu to Wu and was consider a patriot.
Su Qin of the Warring States was the prime minister of 6 states. Can you imagine someone nowadays to become the prime minister of 6 nations that are fighting each other?
In 3 Kingdom era, many loyal generals of Cao Cao were POWs. Zhang Liao would be a good example. He was captured by Cao after the battle of Guan Du and surrendered and became one of Cao's most trusted captains. Zhang He was another example. On the side of Wu, the most famous general of Taishi Ci, who fought the second leader of Wu (Sun Ce) and was captured and became his loyalty follower. Ont he side of Shu, Jiang Wei was also captured by Zhuge Liang in Hanzhong and actually became Zhuge's student and most trusted general. Two of the five tiger generals of Shu were POWs, Huang Zhong and Ma Chao. Also Meng Hue (spelling?) who was captured 7 times and eventually surrendered to Zhuge Liang.
In Tang dynasty, some of most famous generals were POWs. All the generals from Wa Gong mountain surrendered to Tang after a short conflict between the two sides.
In the early Song dynasty, the famous Yang family used to generals of the Late Chen State and surrendered to Song and became the most trusted generals. And Yang Zaixing was captured by Yue Fei and surrendered to Yue.
I don't think we are talking about high-profile captives since these are exceptions. I think we are indeed talking about average soldiers since we are talking about cultures. As Finn mentioned average soldiers in Mid Ages were normally killed when captured. I think this supports my point.
About the Autumn and Spring and Warring States, I think the political control was a lot looser as many different views were allowed to thrive, such as the hundred groups of thoughts. Basically, people back then in China had freedom of speech and freedom of religion that contemporary Chinese don't have. Compared to only ONE political view allowed in China NOW, the political control back then was a lot looser.
First, let me quickly address the issue of "hundred schools of thoughts" during the Warring States era. I disagree that it was because of a "looser" political control. Remember that Confucius was always on the run from one state to another because his mouth got him in trouble. That's not greater freedom of speech, just looser border control.
As for the "hundred schools of thoughts", it did not come from a greater freedom either. From Han Dynasty to Qing, not a single new school of thought arose, even as China underwent numerous dynasties with varying degrees of political control, and several periods of anarchy.
No, the reason there were a greater variety of philosophies in the Warring States era is the same reason Europe had more varied religions before the advent of Christianity: there was simply no unifying belief system (of influence) prior to Confucianism. Once Europe got Christianity, or China got Confucianism, all other beliefs got stamped out. That's human nature.
This isn't to say that pagan Europeans or pre-Confucian Chinese were more "free". It simply meant that their religion or beliefs did not matter as much to the rulers.
Now, as to the issue of "surrender", note that I'm talking about popular perceptions, not the realities of warfare. There were over 20k Chinese POWs in the Korean War, after all.
When we're talking about popular distate for surrender, we need to take into account the "good guys" and the "bad guys". In public perception, it's okay for "good guys" to surrender to other "good guys". ("Bad guys" are always prone to surrendering anyway.) What the public really hates is when "good guys" surrender to "bad guys", which instantly turns the "good guys" into something less. There are exceptions, of course, and Guan Yu is the most famous. However, most of the time that's how public perceptions go.
For example, Zheng Chenggong (Koxinga) did not surrender to the Qing, but his grandson did. You can imagine how history judged that guy. Lin Zexu is venerated as a hero for standing up to the British Opium traders, even though he dragged the country into a fight they couldn't win.
, his replacement, is widely villified for ceding Hong Kong to the British. Li Hongzhang, who dedicated his life toward building the Northern Fleet, was vilified after signing various Unequal Treaties. In "Shui Hu", Song Jiang will never be as great a hero as Lin Cong or Wu Song, even though he is their leader, and that's largely in part (IMO) because he was willing to surrender to the corrupt Imperial Court.