If you want a complex form with conditional logic, advanced scoring, user registrations and much more, Formidable Forms is the plugin for you. If you want a contact form this plugin works excellently for that too, it’s much more power than you need but it is a good solution.
Formidable forms has an easy-to-use graphical interface to build forms, and then can add conditional logic/assign scores or values to responses right there. If you need to refer to the value of a field in the value of another field, email it or otherwise use it elsewhere in the form, you can just refer to the index number associated with that field or use a url parameter right in the Formidable Forms interface.
If you need complicated and very powerful forms on your site and do not want to build them with code then this is the plugin for you.
There is even a very useful API add-on that I used at work to create API sends to specific endpoints and with specific data including but not limited to the data entered on the form.