Some backlinks are inherently more valuable than others. Followed backlinks from trustworthy, popular, high-authority sites are considered the most desirable backlinks to earn, while backlinks from low-authority, potentially spammy sites are typically at the other end of the spectrum. Whether or not a link is followed (i.e. whether a site owner specifically instructs search engines to pass, or not pass, link equity) is certainly relevant, but don't entirely discount the value of nofollow links. Even just being mentioned on high-quality websites can give your brand a boost.