How they compare
Both are free to join and browse, with messaging behind a paid plan.
Victoria Milan, running since 2010, is for married and attached people looking for affairs, with tools to anonymise your profile and keep your identity private. Profile quality and activity vary a lot by city.
Fling.com is a long-running site for casual hookups of any kind. Most features need a paid membership, and it's smaller than AdultFriendFinder.