Advantage of the AdSense Deluxe Plugin
There are two well known plugins for WordPress that allow you to integrate AdSense ads into your blog: AdSense Manager and AdSense Deluxe. For some time I was using the AdSense Manager plugin, because it was much easier to configure. All I had to do was enter my AdSense ID, choose the colors, and the ad type. This made me wonder why anyone would bother with using the official Google Ad generator, and copy pasting it into the AdSense Deluxe plugin. But after some time, I started to realize why it was this way.
AdSense Manager has features that no longer work.
Since it is no longer being worked on, it does not follow the latest Google API. For example, custom channels do not work. After looking at the official code from Google, I noticed that their format for specifying what channel an ad belongs to changed. Also, I had a click through rate close to zero, even though I was getting over 200 visiors a day, and different statistical webpages were reporting clicks on the ads. This points to the fact that you might not be getting credit for all the ads shown on your website.
AdSense Deluxe is not limited to one advertising network.
This is the biggest advantage of AdSense Deluxe. Since you can paste any code, from any source into it, you are not limited to AdSense. This is very good, because to maximize your revenue, you need to use several ad networks. If you are only using one network, the ads shown on your website will be always the same, therefore the returning visitors will have no new reasons to click them.
Also if you write a very long post, you might want to embed several ad units in it. This is a very bad practice. Advertisers that have a higher rate per click will be shown first, and these are the ones that you want your visitors to click. If you have too many ads, there is a good chance that the low paying ads will be displayed, and your visitors will click them instead. However if you have only one ad from each ad network, then all ads will be the highest paying ones.