tl;dr: I do not have any specific recommendations.
I think it depends on what sort of "form builder" you're looking for. PHP frameworks like Laravel or CodeIgniter come with functions that can be used to build the HTML you want, which you could combine with something like Bootstrap by adding desired class names to the form elements to help with formatting. You still have to write code, but hopefully less quantity and complexity of code in order to output the desired HTML.
The other end of the spectrum might be some sort of WYSIWYG tool that lets you drag-and-drop form elements and apply themes to get the desired look. These often have the unwanted side-effect of producing non-optimal mark-up and possibly non-disability-accessible -- so research them carefully.