I don't have any experience with western languages other than English, but Mandarin is the hardest language that I'm learning. I hate the pronunciation, they have different tones and the meanings are often totally different by each tone... but the hardest are the characters. Even if you know the meaning and the writing of each character, their meanings will differ once another character is mixed in to form a new word. Not to mention those phrases that are hard to interpret >.<
Japanese is fun and easy to learn, though I hate it because it shares the same kanji as mandarin, but you can understand a lot just by understanding the hiragana. I have no tutor and now I'm slowly learning it either online or by watching anime. If you understand japanese, you can watch anime that are not subtitled, read manga that are not translated, or the latest video games without the need to wait for months before the English versoin is released. Those are massive advantages in the entertainment world, mind you.
