Sections of the Great Wall: Jiankou or Simatai?

I want to go to the Wall in first days of September. I'm planning to have whole day from 8:00 to 6 pm for hiking through one section. I don't know which one to choose between Jankou and Simatai. I'm looking for amazing sightseeing (the most important), challenging hiking (but not dangerous for life) and not crowded as well.
Can you suggest which section is the best and which path should I take so?
Thanks.)