If I want real target visitor I will use Adwords and AdCenter, if I need general visitor to build brand I will use buyandsellads.
Google works best for me. Infolinks is great but the revenue per click just doesn't compare to Adsense
World is changing. Mobile is coming big way. High time to diversify and get penny clicks from mobile networks while it lasts.
Adsense have main advantage because it's huge. So they also will find some ads for you. But in this way you need to be competitive to others publishers and then you can get better ads than them.
Google is the best advertiser for business but now this time Facebook is also become a good advertiser.