This is my favorite Contact Form plugin and usually has the least amount of bugs. You will want to also download the ‘Contact Form 7 Submissions’ to make sure any submissions don’t get lost between your site and your email inbox. It is more for those who know code and not as user-friendly for non-tech people as others plugins, but it makes it easy to create so many options including adding an opt-in for MailChimp or adding more questions depending on a previous answer