What's really interesting is that people are so interested in the idea that there is a "most difficult" language.
As someone who HAD to learn English in order to survive, since in my time there were no government handouts, and really, no self-respecting immigrant would have taken it, had it been there, let me say that English is a very easy language to learn.
When I was in high school, I was told that when you want to learn a language, learn grammar. It makes no difference how many words you can translate.
If you think in your mother tongue and try to express your thoughts in English, translated word for word, you will sound idiotic.
The same teacher said that grammar is like the skeleton in the body, if you don't know grammar, you don't know the grammar your language will collapse when yo try to speak.