Which essay prompt would be the best to answer? Why?

This depends entirely on your *personal* academic comfort with each of the topics and background material. From my studies, although Juliet is an important dramatic part, her actual life situation is easy to trivialize. Her personality is passive from her upbringing, and her volition in the play is mostly reactive to other characters. This point would serve you specifically in either 2 or 3, and might help support the "fate" argument in #1.