Taran Zhu would be a better leader than Chen Stormstout or Lorewalker Cho, he knows how to lead and has had an army protecting Pandaria under his command for decades. His personal combat skills are of high quality, he is sworn to protect Pandaria like all Shado-Pan are and he thinks with a straight head instead of his heart. Chen has combat experience but no apparent large scale leadership skills or detailed knowledge of how Pandaria operates as a nation, and Cho is just a historian with no tactical or martial prowess.
Taran would be a good emperor. Cho would be an excellent advisor to an emperor. Chen, well he values his freedom to adventure across the lands too much, I think, to take any political position. But if placed in the position of an emperor he would struggle due to having no experience and since he is not really a pragmatist like Taran.
Sure, sure; give the pandas a xenophobic warrior emperor, it worked wonders for us!
Taran Zhu isn't xenophobic. He was
xenophobic when MoP started, and with good reason considering that unknown soldiers landed on shores of the land he is tasked to protect and started to destroy, plunder, war against each other and use locals for their battles, all the while feeding the sha in the process. He was hateful as well, going so far to get corrupted by the sha himself. But once he was saved from corruption he became more accepting of the outsiders and learned that they are not completely bad during the Townlong Steppes questing. Later during the Isle of Thunder campaign he worked with both the Horde and the Alliance, allowing his agents to help them and accepting help in return. He didn't evict the Horde from the Shrine because he saw that there is a distinction between Garrosh's followers and others. In Shadows of the Horde he accepts a troll and a human into his monastery and has his monks nurse them back to health.
He has changed from what he initially was, just like Jaina is no longer a peaceful diplomat. Like he has said to Garrosh: "I have fought beside the tauren, trolls and others, you are nothing like them." he obviously makes a distinction between one group of outsiders and another and is aware that some are not as bad as others.