Which tool to use for automated form posting?

[CasperJSNewbie]

We're working on a small project to automatically post forms across multiple pages (e.g. login form page to enter credentials, then account details to enter name/age/gender, etc.). We're trying to figure out if we should be looking at Selenium, PhantomJS, CasperJS, or some other tool. Can anyone here provide some insights about which tool might be best suited for automated form posting?

We're not trying to develop unit tests. The purpose of the project is to submit forms to a live website.