Latin is more complex as you have to conjugate nouns and adjectives as well as verbs, plus you have tenses such as the ablative and vocative which French doesn't.
That being said, you won't have a speaking exam in Latin, whereas you will in French.
If you have any desire to take Classics at university, the Latin will be more beneficial. However if you're going to go down a more modern languages sort of route the French would be preferable