One or two expensive subscription solutions appeared to be comprehensive, but in the end the freedom of a reasonably priced, powerful Joomla! component that I would have full control over won out.
BreezingForms has a lot of powerful features such as programmable validation scripts and paging and sectioning that make it possible to switch off parts of the form conditionally.
I am still a beginner, but the results are already impressive and the data in the back end easy to export and manipulate.
When I ran into a problem with the form not progressing from Page 1 to Page 2, I tried out the support. I had taken out a subscription, but even so I was impressed not only the quick response, but that they came back with the correct code where I had made a mistake in a custom script.
All is working well now and I am looking forward to completing my project on time.