I think both are good for link building. If you posted your link in only do follow attribute. Its abnormal and search engines will penalize the link.
Basically "DoFollow" is an internet slang term that Websites that are not using "NoFollow". Dofollow links allow to search engine to give a creditability to outbound link. major search engine only follow dofollow link to calculate website pageranking.
Everyone said right. Do-follow links provides backlinks and no-follow links are not helpful in backlinks.
Dofollow links are more effective than nodofollow links. There is a free mozilla ad-on to determine if the link is dofollow or nodofollow. Just type the "nodofollow" in the google search bar.