I have been using Meta Box and while its front end form is good (and I love Meta Box), I would have had to use a lot of custom code to do what I needed. I tried a couple of other pro form builders before this, and they didn’t work for me. I then bought the pro version of WS Forms – and it fixed all my issues.
WS Forms made it very easy to add and layer complex custom logic and actions. It took me a little while to get used to all the features (as there is sometimes too much control over every aspect). But thankfully Mark had the patience of a saint and went out of his way to offer (lightning speed) support. (Thank you Mark!) And after it starts making sense, it is indeed a very powerful tool that will do all you need – and more. 5 stars.