It really depends on your topic and the responsiveness of your visitors to the ads.
What I did is to experiment using Adsense and YPN on a newer site giving the two equal number of impressions using an ad server (I use PhpAdsnew). I wanted to see which ones would attract the more clickthroughs and deliver the higher income.
I run the experiment for two months to give me more solid results. Given the nature of my site (small/home business information), I found that Google Adsense worked 5 times better than YPN. With roughly the same amount of impressions, I earned 5x more with Adsense than YPN. Adsense ads were better targeted and possibly better paying compared to YPN.
I suggest you conduct a similar experiment (making sure that they are not shown simultaneously on the same page as that is against the TOS) and see which ones work best for your site and your topic. Only by testing and seeing the results can you have any conclusive answer to your question.
One thing to remember — our mileage may vary. What may work for me (or for anyone else on YA for that matter) may not work for you. Run the experiment and determine the results for yourself.
With the results I got, I focused on Adsense. It is now giving me more than 5 digits a month (and I don’t mean the low 5 digits)