My go-to is Gravity Forms.

However, I recently needed a solution for a client who was experiencing brute force attacks on multiple areas of their  site where the content was protected by a login form that was being generated by a shortcode. This method was that preventing plugins like reCAPTCHA By BestWebSoft from generating a CAPTCHA on these specific forms.

WPForms made it super simple to create a login form with Google reCAPTCHA enabled that I used to replace all of the custom shortcodes with. From what I had found, they are the only plugin out there with templates built in for creating login and registration forms. Very nice feature to have.