Pursuant to Dave’s response, I have just started using The Form Tool Pro. There are three levels: free, Pro, Doxsera. It depends upon the level of functionality that you want. I’ve settled on Pro for form creators and the free version for form users. It is simple to use and very functional. For instance, you can place conditions upon parts of the text so the text appearing in the final document depends upon the options selected by the user. You can also tailor the document for singular/plural and pronouns for masculine/feminine. There are also math functions. I taught myself to use it in an afternoon, and it is less expensive than Hotdoc by a considerable amount.