I’ve used the EE contact form, but validation seemed a bit wonky and seems like I wasn’t able to get option buttons in.
I’ve used the FreeFrom module from SolSpace (mental note to shoot them some PayPal $) but found that while the validation was much more straightforward, and putting all the entries into the EE modules interface is nice, the current version’s “no duplicates” feature prevented it from working nicely for a Contact Us form. An older version is sufficing for the moment.
I’ve also used “FormMail” on a previous pMPro project as it was suggested by Nevin.
I keep looking at the standard EE weblog with its custom fields, validation, SEF, and new entry email notifcation thinking that setting it up to be used by non-logged-in users would be a nice platform for web-based forms.