I have been into online earnings quite for many years now. I started my writing on HubPages in the year 2009 and then moved on to start my own blog in Nov-2011. Since then, I have been running 5 sites with different ad networks. So, here is my experience with different ad networks which might give you some information.
Adsense: This you might have known is quite a famous ad network run by Google Inc. It is a CPC and CPM based contextual display ads model. It is probably the most simple and also high paying ad network.
However, to make good money one must have huge traffic like at-least 10k visits per day. In such a scenario, the adsense advertiser would take notice of it and would bid ads for your site. But for this, you must enable custom channels to your ads.
Some issues I noticed with this ad network is the constant fluctuation in earnings, slow site pages, and strict warnings and penalties.
I did signup in 2008 so it was easier then and got it even without a website. But now, it is hard and the adense team will accept your account and site after proper verification of content and traffic.
On the other hand, if you are a premium publisher, you will have a dedicated ad manager and you can select high paying ads to run on your site.
The payment is directly into your bank account in most cases by wire transfer.
Then I came across Chitika, BidVertiser, Kontera.
Bidvertiser is a contextual ad network with better ads and minimal payment threshold of just $10. Payment options include PayPal, cheque, wire transfer.
If you have a new site or have been banned by other major networks it is good to try their ads.
Kontera was an in-text advertising platform. It really compensated well with adsense.
The ads look like the links in the text. I was even paid decently by this network but latter I did not continue.
The reasons is that these two ad networks do not seem to have enough advertisers then. So, I kept on with Adsense due to its simplicity and huge advertiser network.
Media.net: This is said to be a yahoo and bing ad network. It is easy to signup and if you have a website with genuine traffic, you will be accepted for the program. You may read our detailed media.net review
They also have contextual ads, but the CPM and CPC do not seem to be clearly defined in the stats on the dashboard like the Adsense.
Further, many publishers complain of very meager revenues for a huge amount of traffic sent. This could be due to the quality of traffic. In general traffic from the US, UK, Canada and Australia seem to be earning much. If you this sort of traffic you can try it. But I suppose that one should try media.net only if you are banned by google adsense.
Compared to adsense this is a not well-paying ad network.
Infolinks: This is an ad network with both text and display based ads. However, if one uses all the variables, it would appear to be too intrusive leading to disturbing user experience. So one should use them with certain limits.
They have good quality ads and can be used on almost any topic of websites. However, the income would be low for the impressions you generate. But it can be used along with Adsense and hence can act as additional revenue source on to your site.
Revenuehits: This is another good ad network which can be considered as adsense alternative. But, this system has popup ads besides the display ads. They have payment options through PayPal, Payoneer and even wire transfer. They have prompt payment with decent revenues. Only thing I was not comfortable with them was due to pop up ads which can deteriorate user experience. Read more from our revenuehits review.
Adsterra: This is the ad-network which upset me the most. After enabling their ads, Google dropped our site rankings. Once, we completely removed their script from our site and applied for reconsideration, then only we got our traffic back. The issue was their mobile ads were redirecting even before our site page from search were opened. May be now they have improved their ad monitoring system. But still their revenues were low so did not go after them again.
Ezoic: Of all the ad networks, this is the best in terms of revenues and ad quality. The only problem comes if you have a WordPress site which is very slow. Because their ads slow down your site due to header bidding and will finally lead to a traffic drop. But one of my friends could manage it well. He reduced the number of ads and also the number of plugins in WordPress. Then the site was fine and so was the revenue. If you thin your site is well optimized, then go for ezoic as you will never turn back.
Exmarketplace: This is a low profile yet promising ad-network. They just run google double click ads. Since they manage it from their side, you will not need to make any efforts on the ads. They pay in time and assign you an account manager. Try out exmarket place if you wish to have better revenue than adsense without a decrease in site speed.
If one has to make more money with decent user experience, then the number of ads should be low but the inventory should be high.