This isn't the place to evaluate history, but I used to like the things you like now very much (for example military affairs, politics, history, though now I'm no longer interested), so I'll say a few more words.
The reason the Kangxi era isn't as famous as the Han and Tang eras is not because of personal ability, but because of the changes of the times and of history. A person's lifespan is only a few decades, while a historical stage lasts hundreds or even thousands of years. China is an ancient civilization. By the time history developed to the Han and Tang periods, it was precisely the most prosperous era in Chinese history. That doesn't mean it was the achievement of some one emperor or some one dynasty, but the effort of several generations or even dozens of generations. Liu Bang, Emperor Wu of Han, Tang Taizong, Wu Zetian, and Tang Minghuang merely played especially prominent roles. But what was Japan like at that time? Where was the West, did it even have civilization? So naturally, in that era, the Chinese nation was the most outstanding nation. But as history developed, the West and Japan kept rising while China declined more and more. This is not the problem of one ruler or several rulers, but the natural law of development of the entire feudal society (as the times developed, the feudal system had already become the greatest obstacle to social progress). By the Ming dynasty, tiny wokou pirates were already stirring up trouble so badly that we could not live in peace. By the Qing dynasty, only in the Kangxi period was the only equal treaty with the Western powers signed. In my view, even if Li Shimin had been alive then, could he alone have turned the Qing dynasty into the Han-Tang era? The same applies if we use the present as an example. Can any one person immediately make our country as strong as America? Was it Mao Zedong or Deng Xiaoping? It still has to be done step by step over several generations or dozens of generations. And all the while you have to make sure no saboteur appears. Even so, reaching the glory of the Han and Tang periods would still be impossible.
Kangxi allowed foreigners to serve as officials, which shows he was not closed off at all. It's just that everything has its historical environment. Kangxi did make some mistakes, for example some literary inquisitions, but those cases were rare. It was only because he wanted to consolidate the Manchus' position; after all, as you said, the Manchus were not the legitimate orthodox Chinese line. It's just like Li Shimin killing his brother and younger brother and forcing his father to abdicate. There's no logic to it.
Kangxi's charisma influenced several generations. Among them, Qianlong especially admired this grandfather of his, and that is why there was the flourishing age of Kangxi and Qianlong. Frankly speaking, if not for Kangxi and Qianlong, feudal society might have ended in the early Qing period. It was Kangxi who let feudal society live another two hundred years.
As for the Taiwan issue, it should count as one of Kangxi's great achievements. Not only that, it is also the best point of reference for us now. Actually, our present situation is very similar to Kangxi's time, except they solved it and we still haven't. Hehe. ... I wonder what DD thinks of that.
By the way, about the TV drama Kangxi Dadi, it mainly evaluates Kangxi from the angle of the person. What it depicts more is Kangxi's inner psychological world when facing political struggles: unbearable pain when facing internal factional struggles, boundless joy when facing victory in war. What left the deepest impression on me was one line he said when he recovered Taiwan: "At this moment I feel how happy it is to be emperor." On this point, it was mainly that Chen Daoming acted well. But the TV drama did not fully reflect Kangxi's great achievements.
One last thing: you have ethnic prejudice, and that's not good.
http://dos.e-stone.cn/dosbbs
uploadImages/200311161145850422.swf