can't say but German is quite complex for no real reason!

English.. I never realised it until I had to learn it in order to teach it - and it's my native tongue!

Slavs languages are far more complex than English or German.

RUSSIAN IS THE MOST COMPLEX 98% OF RUSSIAN WORDS ARE AFFECTED BY THE GRAMMER AND THE GRAMMER IS WICKED SO IF YOU DONT KNOW RUSSIAN GRAMMER YOU CANT SPEAK RUSSIAN BUT THE GOOD THING ABOUT IT IS THERE IS A SMALL TABLE OF GRAMER RULES IF YOU MEMORIZED IT YOU MASTERED THE GRAMMER

Definitely Japanese.

In general, older or more conservative languages have a more complex grammar than more liberal ones. So a language like English is much less complex than a language like Standard Arabic (also known as Fushaa), because Fushaa has been the language of scholarship and prestige since the birth of Islam over 1400 years ago while English was considered a vernacular tongue until more recent times. Even today our vocabulary isn’t very productive in itself and we turn to languages like Greek or Latin for coining words to describe new concepts or discoveries. Oh, and German is NOT a complex language. German is actually pretty average in terms of complexity for a European tongue. It only appears that way compared to English or Dutch, but it’s nothing compared to Sanskrit or Fushaa. I’ve been studying Fushaa for well over a year now and I can testify that in addition to having a highly complex grammar, Fushaa is overrun with countless synonyms for even basic words. I’ve encountered two words for lizard, three words for bus, and three words for store. It’s also very specific, so there are different ways of saying a word like “water” if it’s a normal amount (maa) or a large amount (miyaah). Finally the plural form often bears little resemblance to its respective singular, and there is a dual form in addition to plural. Sadeeq is “friend“, asdiqaa is “friends” and sadeeqaan is “two friends”. It’s possible to be able to speak and write the language very skillfully, but still not understand what other people say or write because of how immense the vocabulary is. The phrase “both of you were drawn” is just one word in Fushaa (rusimtumaa), because of the complexity of the verb conjugation.

Well, it's very difficult and I even would say impossible to determine the most complex language. First, there's a difference between hard and complex language. Hard language can be very simple, like, for an example, some dialects which gramatically appears to be elementary, but phonetically are reacher than many other languages therefore very hard to speak for some groups of people. If you want to measure an compare the complexity of different languages there're a lot of things to take into account, such as grammary, structure, quantity of words, etc. Basically, more complex the language is, more precisely it expresses the events around and transfer the feelings and thoughts of the speaker, which automatically is going to imply that it is going to have a huge variety of words, a very developed frame. Then, variety of synonyms could result from the the size of a country or the number of countries, the language is spoken in. Jamaican English has some words proper to itself, as well as Canadian French does. Thus, I don't really know which base should be taken to determine whether a word concerns the language or a dialect based on the language. People generally tend to answer this question by claiming that their mother tongue is the most complex and the hardest to learn and to speak. I visited a lot of different places and meet a lot of people of different nationalities, and 9 out of 10 answers says the same thing when speaking about languages. This is kinda pathetic, because the essential thing is not to speak a complex language, but to speak it well (which is pretty rare even for those who have a degree). I speak Russian, French and English, last year I started Spanish and I could say, that for me it's hard to learn any foreign language. Spanish seems to be easier to learn for me, but only because of my proficiency in French. That's my brief answer. ;)

Linguists will tell you that it is Chinese. It takes the longest for the children to master and for foreigners to learn. It also is the language that utilized both sides of the brain the most.