Sanskrit has an hellishly difficult system of letter-changing called Sandhi; it comes in two forms: internal and external. If you were to look at a line of Sanskrit text, it would look like a a language filled with extremely long words. It's not. Instead, each of those long lines (eg. समन्तपञ्चकम, or विचित्रार्थपद
With about how many other languages have you a sense of acquaintanceship? The manner in which your argument is writ would suggest that you want others to believe that you've a background in the topic which you are discussing, but the substance leads me to believe that you are simply repeating an oft-heard line with which you've no scholastic background. Throughout my manifold studies, while I will not deny that the number of barriers that must be crossed in learning English is large, there is still a sense of regularity and, with enough experience, can often be predicted. While this may be true for most languages, English is far from being one of the hardest modern languages to learn. Whilst it is true that there are many tongues which would rank ahead of English in terms of ease of acquisition, there are also many, many harder languages. I shan't discuss Old Norse, Latin, or Middle High German - the ancient tongues with which I am most familiar - merely because of your reference to modern languages, but of those languages which fall under that heading with which I am also familiar, I would have to say that French and German are harder. Swedish, Icelandic, and the other Romance languages are relatively easy, though this summation is coming from a native speaker of English. Sanskrit is, by far, the hardest language which I have ever studied, but it, too, is closer to the category of ancient than to modern, despite still being spoken as a native language by a number of individuals. The Celtic languages, though I am not very well acquainted with them, are also quite difficult, the grammar being far removed from that of the Teutonic and Romance tongues with which English is most closely related. Then, of course, there are the Uralic languages; namely Hungarian and Finnish, the difficulties of which are infinitely greater than those of the other European languages. I fear, though, that I have focused too heavily on European languages; thus, despite being mostly ignorant in them, I shall now repeat that which I have oft heard. Arabic is, I have learned from those who have studied the language, very difficult not so much in the grammar but in the manner in which the language is writ, for vowels are so often omitted from writing, as with the other Semitic languages. Korean is also an extremely difficult language, having a hellishly complicated system of honorifics. Chinese, like many of the other East Asian languages, is difficult more in its pronunciation and writing systems than grammar.
It depends on how you yell it. Right now I'm envisioning a beach so crowded you can barely move, and an hysterical woman pointing to the beach and screaming at the top of her lungs: "Tsuuuuuuuuuunnnnnammmmmmmiiiiiiiiii!!!