In the online dating world, AdultFriendFinder and Plenty of Fish are certified OGs. These veteran dating sites were first established more than two decades ago, before both the social media era and the smartphone era. Yet both sites have continued to stay relevant, attracting millions of visitors from all over the world searching for connection.

That, however, is just about where the similarities end. In fact, you’d have a hard time finding two online dating sites less alike. Plenty of Fish operates like a conventional dating site, even adopting the smartphone-like “yes-or-no” carousel approach.…