[ard0r]

We have both on the contact page, and we get more people filling out the form than emailing us, which I guess is surprising but the contact form is right there whereas the email link is a click away.

I really prefer them to fill out the form, because when we can associate their message with their browser, cookie, and IP address, I can get all kinds of useful information eg whether they came from an AdWords link, how many visits to the website they've made, whether they've ever clicked through a newsletter, their IP address (which I can use for geolocation), whether JS is enabled, etc etc.

I also find that it's easier to block spammers via the contact form than the email link, because of all this information I know about them.

[chalst]

I also find that it's easier to block spammers via the contact form than the email link

Definitely. Even without looking at information like cookies, IP address, it is much easier to filter comment span than email spam.