Is there any good network with high fill rate, ecpm and good revenue (without using admob) ?
no ad network will fill your requirements except admob. If you don’t want to use admob, use some mediation networks, like appodeal or adincube.
Don’t know about best. But I can tell about worst and that is Startapp.
Worst? hahaha…worst is airpush, they are displaying porntube ads to my users with ****s, blowjob or ass ****ing