It depends on what kind of vertical you're into. Each network more or less specializes in some types of verticals. There's some that are more generalist, and others that are very narrow in scope.
CJ.com is beginner friendly and very broad.
Clickdealer.com has wide range of offers.
Clickbank.com is a well known marketplace with info products.
Crakrevenue.com &
LosPollos.com are well known on BHW for adult dating CPA offers.
MaxBounty.com is a generalist network with many offers.
Adbluemedia.com Cpagrip.com Ogads.com if you want content lockers.
Lastly check out
Offervault.com (offer search engine) and
Affpaying.com (Affiliate network reviews).
If you meant the other thing -- buying traffic to send to offers, see Google Ads, FB ads, Bing ads,
TrafficJunky & exoclick are big for adult.
You can always hit bhw search bar with a query like "popular ad networks".
