Its important to knwo up front that NONE of these so called 'advertising networks' actually tell you how much they pay or for what. Therefor, you have to experiment and intuit. These are the
results of my experiments to date.
AdMob.
The Good:
AdMob is the 800 pound gorilla in this space having been bought by google. Their sdk is the most mature and easiest to integrate. Their ads are also the least intrusive. They will also run your "house ads" for your own products in your other apps for free. Finally, their reporting tools are *excellent* and really give you a good feel of the trends of usage of your app.
The Bad:
Unfortunately, they also pay the worst of all three. Although they don't publish their exact formula (none of them do) it semes to be *heavily* if not entirely base on click through. I've served almost 7,000 impressions, but only had 14 click throughs. Total revenue: $0.88
Quattro.
The Good:
Quattros ads are still fairly unobtrusive, about twice as tall as an AdMob ad. While the SDK is a bit less mature, it is a bit more automatic. AdMOb's view has to be told by your app when to get a new ad. By contrast you just place the Quattro view and tell it how often you want to change ads and it does the rest.
Quattro pays for impressions as well as click throughs and it shows in your revenues. With about 6500 impressions and only 6 clicks I already have made $1.44. Quattro also encourages a faster ad-flip rate and thus Ive gotten those 6500 impressions in something like a third the time it took for AdMob, who I integrated earlier.
The Bad:
Quattros analytics pages frankly suck. You cna ask for number between any two dates but what it shows you is the aggregate total over those days, not numbers by day. This makes trend analysis very hard. They also don't have "house ads". Finally, while their view is easier to integrate, you also have a bit less control over it.
Greystripe
The Good:
Greystripe is different from the other two who are primarily banner-ad suppliers. Greystripe specializes in interstatials, ads that take over the entire screen for their run. They imply on their website that they pay per impression. In fact, their reporting tools don't even show click-throughs. This means you get paid for displaying the ad, whether the viewer clicks through or not.
I have found their tech support responsive, which is important given their issues. (See below.)
The Bad:
Interstitials are by far the most intrusive kind of ads there are. Therefor you won't be generating high impression rates per user if you don't want to drive your users away. I have my app configured to display one on launch and then one approximately every 5 minutes. For games, it makes more sense to integrate the interstitials between levels since you cant pull the screen away from the user mid-level.
Their Android SDK is in beta and is by far the hardest to integrate. To begin with, its not perfect yet. My interstitials don't display properly the text on the buttons to go back to the app or to the linked advertiser web-page. (I've reported this and they say they are working on it.)
The biggest problem however is that they chose to implement their ads not as an Android view, like the others above, but as a separate Android activity. This causes your app to go through life cycle call backs that are exactly the same as when a user navigates away from your app and then returns. This is simply a nightmare to deal with, impacts app stability, and needs to be fixed right away.
Their reporting tools are neither as good as AdMob nor as wretched as Quattros.
The OTHER issue I have right now is that they *say* they pay per impression but their reporting tools aren't showing it. I have 158 impressions so far and its still reporting $0 income. This makes it hard for me to get a grip on what, if anything, they are actually paying me for my efforts. Given that the impression rate is so much slower with interstitials, this is an important consideration.
Conclusions:
Right now, for income (which is why we do this, right?) Quattro is the big winner. They aren't terribly objectionable and pay quite well. If their reporting tools were better and they had the house ad option, they'd be the only banner service I'd use. As is however those values are big enough to make me keep AdMob too. At least for now.
AdMob is the second place producer. They are less then half as lucrative from a payment point of view, but their tools are excellent and have really helped me learn user trends from this first product.
Greystripe has promise, but they need a lot of work. The SDK is definitely not done and need some serious re-architecting. And I'm very concerned that their website has yet to tell me I've made any money at all.
In web-advertising, interstitials are a big money maker and there is promise in this market, but Greystripe has work to do if they want to fill that niche.