Most users, whether on the desktop or especially on mobile devices, have an email app and clicking on an email link gives them all the advantages of sending email from a familiar interface, of having a record of the email in the "sent" folder, of having the ability to store your email address in their contact list, and of being able to store a draft of their message to you and continue it at a later time. Contact forms provide a poor replacement for a fully developed email app and many users balk at being forced to type into a form. Even users of gmail and similar webmail can still copy and paste your email address into their "to" box.

Phone or tablet users are especially likely to appreciate the ease of using their familiar email app because it has been optimized for smaller devices. At the same time, contact forms may be difficult to use on small devices.

Some users, such as those using library computers, may have no email set up, either on a desktop or on a mobile.device. These users can benefit from a contact form on your site.

My recommendation is to provide both. If you are resource constrained, just provide a link. And don't forget to also "linkify" your phone number for all your mobile device users. Here is how to do both:

<a href="mailto:info@mysite.com">info@mysite.com</a>

<a href="tel:+1-555-555-5555">(555) 555-5555</a>