Reliable banner provider to replace Admob


I got mail from Admob this week that the serving of Admob ads for one of my apps has been terminated trough policy violation. Now I am looking for a new provider to replace Admob.
I am currently using Amazon and Mopub, but I need a network with good fillrate to backfill those two. Any suggestions?

MMedia maybe? They have similar eCPM to adMob (in my case) but are a little unreliable sometimes and sometimes their eCPM is much lower (especially since they tend to pay more than your real earnings are).

I have started to move away from banners. Only admob can fill all world traffic for banners, other banner ad networks are for tier1 countries. Airpush used to be good for tier 2/3 also but now ecpm is not worth the constant banner ads when screen size is at premium. I now prefer showing interstitial minimum 2-3 times than banner ads.