To learn Japanese, you have to cover:
So I think it's a challenge to learn Japanese in the first place. But I still think the grammar is ridiculously simple. Only two verbs in the entire language are irregular. The spelling is fairly simple. And most of the elements reinforce each other. I am actually thankful for kanji, cause sometimes it's the only way I remember a word's meaning, and there can be nice nuance communicated through them (見るvs.観る for example).
Anyways, I don't really think I need to go into why English is harder. But I will share this link with you. Maybe you'll see my point through it.