Actually, on the whole, languages are just about equally complex. It's just that the complexity lies in different areas. French, for instance, has a more complex verb system and English has more irregular verbs. French has gender in nouns which is hard for English speakers, and English has a complex set of verbs + prepositions (things like take up, take out, take in, take off, take down, take on, etc. which have very different, almost random meanings that have to be memorized) which is hard for French speakers. Both have ridiculously complex spelling systems though.