Best PPV or CPM Banner Ad Companies?

I was wondering which Pay Per View Banner company's have you used and been paid with before?

Currently the only CPM that is working for me is a pop under but i have 4 available 300 x 250 Banner ad slots.

I am currently thinking if i can find 4 company's then that is 4x the profit? so if anyone has any good suggestions for banner ads that would be great.

You can take a look on PropellerAds Media, Exoclick & Revenue Hits. Among these Ad networks PropellerAds is offering highest CPM.