Which mobile ad type to use?

I want to add ads to my mobile app, but I really don't know how much money they bring and which type of ads brings more revenue, video/image/banner/etc. Please give me some advice if you dealt with this staff before.

In theory interstitials (full screen ads) should give you more money.

However in the real world only 1 thing matters: where are your players from?

1000 interstitials showed in 1st world (USA, Canada...) can give you 2-3$ (or more)

1000 interstitials showed in 3rd world (Asia...) can give you 0.2-0.3$

doesn't watching 15 sec video bring you more than just full screen ad appearing on the screen?

i use chartboost interstitials