(streams) and Forte have very nice user discovery: On your stream page which is always the landing page when you open your channel, there's an area to the left which suggests two new contacts to you. The same thing is on your contacts page. Below the two suggestions, there is a button to a suggestions page which is basically a special, filtered version of the directory. There you get even more contact suggestions. The two suggestions are randomly picked from the two on your suggestions page.

If you fill out your profile, especially the keyword field, the suggestions will improve. Also, the suggestions may include not only users, but also whatever qualifies as a group, because the directory certainly does.

It's basically like Facebook, but more convenient than Facebook has ever been AFAIR. Friendica has had this kind of suggestions since its inception in 2010, and (streams) is an indirect fork, so-to-speak. I don't know if Friendica has a suggestion field up front nowadays, though; I know that Hubzilla doesn't have one unless you add it using the PDL editor (and, please, which newbies dives into Hubzilla that deeply), and (streams) and Forte do have one.