In my opinion, I have a set of rules when choosing a cpa network worth joining:
+ Long-standing: Network must be over 3 years old
+ Transparency: never been complained about
+ Reputation: they are mentioned in many forums and spend money on advertising regularly, participating in affiliate events is also a plus
+ Fast and regular support
+ Large number of offers
+ Payment frequency
Based on the above criteria, some names are worth considering such as: Maxbounty, DMS, Dynu In Media, Clickdealer... you can join to try