OkCupid: Compatibility percentages come from shared Match Questions, while search and ranking can use preferences, activity, and paid filters. OkCupid has publicly described "attractiveness" sorting as based on how many Likes a member receives. WHY THIS SUCKS: A compatibility percentage looks scientific as hell even when it is still a recommendation system built from answers, filters, popularity, and whatever the algorithm decides matters. Dating should not feel like filing taxes with a hot-or-not sidebar.
Match: More traditional search and result lists, with paid Boosts that place a profile among the top search results for a limited time. WHY THIS SUCKS: You can pay to join, then pay again to appear higher in the results. That is a cover charge followed by another fucking cover charge so people can notice you are in the building.
Facebook Dating: Suggested matches use Dating preferences and profile information, plus signals such as shared Facebook Groups, Events, and other activity. It is less swipe-casino-looking, but it is still a recommendation feed. WHY THIS SUCKS: Facebook already knows your aunt, your high school, and every weird Group you joined at 2 a.m. It does not need to rummage through that entire damn junk drawer to decide who you should date.