I have to agree that Gravity Forms is excellent, this is something I have wanted to have for a while now. Other form plugins just don't match the ease of use that Gravity Forms gives you. With the other plugins I have also found that they can be good but there are always problems with them that I encounter which can waste time where as Gravity Forms lets you get on with what I are good at.
What clinched the deal for me buying it was the valuable support that I have already received, being one of the first to test out the demo site and see it running was brilliant and worth every penny.
I very much look forward to what the team have install for us in the future