Best banner ad networks?

I’m looking for new banner ad networks as currently I only use StartApp and my eCPM is getting lower and lower each day. I know banners do not perform as good as a few years back but my current eCPM is ridiculous!

These are the ad networks I already know/tested:

  • StartApp
  • AirPush (it performed great but I stopped using them when the Standard SDK started to show the EULA)
  • AdMob (no more Google, thanks)
  • LeadBolt (worst eCPM ever)
  • AppBrain (I’m happy with them, but using AppBrain as the only banner ad network is not optimal).

Looking forward for your replies!