In my opinion, French is way more difficult! The pronunciation, spelling and grammar has no logic at all while German has, although it's easy to simply master it! 

I'm a native German speaker and I think that German is harder to learn than French because of our grammar.

I never learned German, but what I know is it has more genders in nouns than French....which would drive me crazy to learn since I've already suffered so much when learning French...

It depends on the languages that you know, as you might find similarities between them that makes easier learning a language. Gramm in German is more structured but it is also more complex, so it would also depend on each person's skills. You also have other things to consider like pronunciation, spelling, and even historical background, so it is hard to objectively tell whi one is harder.