FormNX

Initially I was skeptical because of the UI but if you're able to look past that (and I believe it's getting overhauled soon) you'll see that FormNX is a feature rich form designer.

Out of the box it does everything you need it to do, if you have some CSS skills and T3, you can easily create beautiful AND functional forms.

Once they integrate custom domains / CNAME, it will definitely be a top contender in the form space.