After trying (and failing) with many premium form builders, I can genuinely say the WS Forms is miles ahead of the rest. What separates WS Forms is that it has highly granular functionality and control for form creation and is clearly built with accessibility in mind. That alone is something where many others fall down.
The other jewel in the crown is the developer behind the software, Mark Westguard, who is a highly experienced developer and very passionate about his products. He is super responsive to his customers and genuinely will give each request time and thought and comes back with a professionally considered solution.
This is one product I am happy to pay a yearly fee for without a second thought as, yes, you are buying a software product, but you are also buying the piece of mind of highly experienced support, industry best practice and a highly dependable product which makes WS Forms worth every penny and more.
As someone who has been in development for over 20 years, I cannot emphasize enough the importance of having data capture done correctly on your website. If you are a serious WordPress designer or developer, this product sets the bar.