The flexibility form.io provides for delivering a wide range of solutions. It comes as an OSS and a well-featured Enterprise (paid) version. Its simplicity is what makes it a robust product. In addition, I could only praise the form.io team for their second to none support.

Flexibilidade, custo, abordagem profissional, suporte

The ability to have less-technical users build forms, using standard fields easily. The extensibility of the forms, by providing own implementations of form-fields