Which App Advertising Network To Use?

[biometrics]

I'm writing free Play Store apps and want to make money through advertising.

There's a lot of advertising networks and the reviews I've read aren't helpful.

Which network do you use and why?

I'd like them to pay to a PayPal account.

I'd rather be paid for installs or displays rather than click throughs.

I'd prefer an http based api rather than a binary.

 

[koeksGHT]

Admob pays best otherwise I use Leadbolt(no where near as good) but they allow ad's on devices where google can't index page(HTML5 apps)