Most Difficult Languages - Polish

I've read about the supposed difficulty of many languages. Some I don't know at all (like Chinese or Arabic, which I'd imagine are difficult), but I did have the opportunity to learn one of the hardest, and supposedly the most grammatically-complex Slavic language, Polish. It is certainly harder than Croatian, which I already knew when I started to learn Polish.

Here's one (somewhat trivial, but illustrative) example of the relative complexity of languages: the number 2.

English, Spanish, Dutch: 1 form (two, dos, twee)

Portuguese: 2 forms (dois/duas) - depending on gender (2 - masculine & feminine)

Croatian: 7 forms (dva, dvije, dvoje, dvojica, dvojice, dvojici, dvojicu) - depending on gender (3 - masculine, feminine, and neuter) and case in one specific form. There were other variants historically but they're not used anymore.

Polish: 17 forms. Depends on gender (3), case for all forms. Pretty much all these forms occur in regular speech (6-11 less often than the others)

Dwa palce
17 grammatical forms for the number 2
dwa
dwie
dwoje
dwóch (or dwu)
dwaj
dwiema
dwom (or dwóm)
dwoma
dwojga
dwojgu
dwojgiem
dwójka
dwójki
dwójkę
dwójką
dwójce
dwójko

źródło: hubpages.com/hub/Most_Difficult_Languages_-_Polish