A dofollow link is the most valuable type of link as it passes SEO value and authority to the site it leads to. Dofollow links are active hyperlinks with anchor text (the text that is hyperlinked) that is typically related to the name or topic of the campaign's content or publisher.
First of all i would like to say this wherever the link build it dofollow. and my favorite way for link build like Forum Posting, Directories Submission, web blog 2.0 and blog comments.