The customizability and the community support makes it stand heads and tails above other offerings.

Out of all of the Form builder plugins I've tried for WordPress, Gravity Forms has been my favourite for its range of features and options and reliability. It's easy to use and provides enough granular control over the different features.

I like the ease of use of building forms that can be embedded anywhere on a site. Plus configuring them for different needs is easy with plugins and built-in features.