For me, the hardest is definitely speaking. I cringe when I hear my accent. And I can't take 5 minutes to come up with the right word. But when I'm reading or writing, I can take my time to figure out each word. So, my writing and reading always appears better than my speech fluency. Also, I think my inhibitions hold me back. I don't want to make a fool of myself. When I was studying languages in jurnior high school and high school, native speakers would make fun of me. I guess that has left its mark. I also like getting my message out there all at once without the "uhs". And so I rarely have the patience to stumble around, practicing. So, because of all that, speaking is the hardest.