For Interstitial ads I had higher epcm with facebook audience network than admob.
epcm is not the problem here, admob terminated 2 of my accounts for invalid clicks without giving a single warning or a proper reason. Ever since then I'm using Fb ads.
I have an investor so I'm planning to promote my game. I can create a whole new admob account to monetize this game, but if my account gets terminated again, all the money I spent for promotion would be a waste. Also, admob suddenly drop their fill rates for newer accounts, sometimes it takes weeks-months to get back the fill rate. This is also a concern.