The most versatile and flexible joomla form builder available.
BreezingForms from Crosstec is one of the more established form builders for Joomla, having been around since 2009.
Compared to some of the other forms, it can be a little hard to navigate and get to grips with the layout and structure of the extension, but once you figure that out, you'll be rewarded with a powerful and flexible form builder extension.
Some of the features offered by BreezingForms are:
Responsive Forms - this is an essential requirement really, it would be more of a surprise if a form builder did not offer this these days.
Multiple Field Types - they have 17 different types of fields, from the standard text boxes, radios, dropdowns etc., to things like PayPal buttons, Stripe payment buttons etc.
Mobile Forms - they have different views for mobile devices, this differs from Responsive Forms in that responsive forms use the same view, but just modify the layout depending on device screen size.
Integrations - they integrate with various third services for messaging, saving forms or updating leads. Some of the services they integrate with are Salesforce, Mailchimp, Google Drive and Telegram.
Multiple Themes - some of these look a bit dated in this day and age, but the ability to theme the forms, and various themes out of the box cannot be a bad thing.
BreezingForms does offer a free version which includes the core features and functionality, but does not include some of the more advanced field types such as invisible recaptcha, or stripe payments, and is also missing the integrations with third party apps.
The premium version comes as part of a general Crosstec license - a license will cover you for all Crosstec extensions, and all templates (on all but the 6 month license, which only includes the latest templates). Licenses will also cover unlimited installations. All in all it's a pretty generous license.