>>12546652German is the easiest language I've ever learned. Spanish grammar is easier, but the way it's actually spoken is harder for an English speaker to parse in my experience. French is just... urgh. All those contractions and unpronounced letters, and somehow they still manage to pack their sentences with unnecessary syllables; the written language literally has a completely different grammar to the spoken one. French is to Latin what ebonics is to English - the fact that there's a central academy devoted to defining what 'proper' French is is a sick joke.
Japanese is the worst language in the world in everything except aesthetics. It is both unbelievably inefficient and difficult for both native speakers and foreigners to learn properly, and if you're an English speaker it's probably the most alien language you'll ever encounter. I would say Japanese is the most difficult thing I've ever learned but I can't really say I've fully learned it, and probably never will.