[cbr]

    I totally believe that it's easier to learn English than
    Mandarin (and maybe easier to learn Spanish than English)
    because the writing system gives you more hints, but that
    doesn't have anything to do with the (spoken) language,
    strictly speaking.

Sorry, I wasn't actually trying to bring up the writing system at all! I put both English and Mandarin in the "harder" category, even though English's writing system is simpler (though still not as simple as many).