Here’s a view of the survey form created with two WordPress Forms plugins, Gravity and Caldera. As Gravity has no free plugin we don’t have the installation number. Caldera is over 100k, which puts it below Ninja Forms and on par with Formidable. Contact Form 7 is the granddaddy at 5+ million, but needs additional plugins to achieve some of the functionality of these other forms plugins. When I last used it I found it too manual for my tastes.
Choose One Form to fill in. If you fill in the Caldera (yellow on the right), and want to be notified when the book is ready, fill in the email form below it and hit the Keep Me Posted! button.