Formidable is hands down the best, most innovative and easy to use form builder for WordPress I've ever used. Calling this plugin a simple "form builder" is a bit of an understatement - people with no knowledge of HTML, CSS or programming can create extremely complex forms with ease.
Blair Williams (Caseproof)
Formidable is by far the best contact form I have seen for WordPress. It is easy to create and has had zero issues with form deliveries. What makes Formidable unique is it’s ease of use and reporting capabilities. Takes all of the guesswork out building a form.