✔ 最佳答案
Like another answerer, I speak all of those languages.
It's hard to say which is more difficult, they are difficult in different areas!
Korean is difficult because of Hangul, and its weird pronounciation rules. Don't let friendly Koreans fool you, Hangul isn't logical!
Japanese is difficult because of its grammar. Japanese people are quite proud of this though...
Chinese is difficult because it's hard to pronounce. I don't find the Hanzi difficult though, but I suppose I've gotten used to it...
So I guess it depends on you. If you're bad at spelling, Korean will be difficult. If you have trouble remembering grammar rules, Japanese will be hard. If you don't have a good "ear", or can't remember complex pictograms, Chinese will almost impossible.