Ninja Forms is a very powerful and effective form creation tool, with a ton of options and very good functionality. It's a bit limited in its basic version, with standard question-field lists that look a little "blah" without custom CSS work.
However, we pair Ninja Forms with Layout & Styles EXT and it really looks great. As a development company with a few dozen different client needs, we really like being able to export and continually edit forms between sites. The unlimited license is AWESOME! Thanks, guys!
**WORD OF WARNING**
This plugin is load-heavy in PHP requests. If you're using a cheapo-hosting option like goDaddy basic or 1&1 (which you should NEVER do if you respect your website), you'll get stuck with inexplicable 500 errors all the time, since a longer multi-part form can easily query 260mb or more. With these cheap hosting options, you can't check your own PHP error logs, since "shared hosting" means "shared logs" so you can't review the logs and debug your forms.
This error occurs while editing a longer form. Your site visitors will never have trouble, but you'll get your form stuck in limbo where you can't edit it since the server can't display the form editor, and you can't export since it won't update the database without the form editor save function. [insert womp-womp tombones]
Overall great plugin though. And good support. Thanks!