Hmmm... I'm rather "skeptical" with the most damaged people are the wisest.
It could either be England or China.
- Brothers always made fun of him, therefore making him lonely....(?) - His "favourite" country (coughAmericacough) left him for independence. - He's the "black sheep" of Europe... - He doesn't have that many friends... except for his magical friends. - Most of his colonies left for Independence. - Even until now... he is still being teased (damaging his pride and self-esteem...) - Imagine his pain when he had to fight against America. - other points I did not mention China: - He's the oldest country... some say that China (the country) actually had inhabitants before most Ancients countries were "formed". So if we apply this theory to the anime... that would actually make China really, really old, and since he's one of the earlier countries who were formed, then wouldn't that make him lonely? Being the only one of his kind. - And even when Rome, Germania and the other Ancientss were alive, he still felt lonely, since only few of them were able to encounter him... even then it's only for trade or war. So he's still lonely. - He lives in a house in the middle of a bamboo forest.... which means he doesn't really interact that much with even his people back then. - He was absolutely happy when he got to take care of Japan, HK, Taiwan, and the others, since he wasn't alone, but all of them left, leaving a deep scar. (Japan attacked him, Taiwan went with Japan, Vietnam was colonized by France(?), S. Korea wanted Independence, HK was taken from him). - He was forced to fight one of his little brothers. Of course it would hurt him. Even now in the present, little to none of his siblings see him as their big brother. Or at least show some sign of thanks for raising them. - He's old, seen many more things than most nations. - other points I did not mention.
As you can see, these two nations have gone through some pretty rough history, so it would only be natural for me to be skeptical on who would better suit "the most damaged people are the wisest".