There are different approaches on how to measure how popular the various deposit methods are. For example, you could create a huge table of the largest casinos, list their banking options and weigh them by the popularity of the casino. We took another, more global approach.
You might have heard of Alexa, a serive that measures the popularity of websites. The lower the Alexa rank, the more popular the site is. The currently most popular sites are Google, Facebook and YouTube on the ranks 1, 2 and 3.
In the following, sortable table you can see the popular deposit methods by Alexa rank. In one column there is the worldwide rank, and in the other one you can see the popularity in the U.S. By far the most popular payment website in the world is the one of PayPal, followed by Skrill and Neteller. You can also see that the Skrill website is still not as often visited as Moneybookers, even though the brand name change happended already a while ago.