Is there one? No, sorry to break the news. The fact is there are dozens and dozens of advertising sources you can take advantage of right now to get your products in front of people. Whether it’s PPC, website ads, banner exchanges, email advertising, traffic exchanges, etc., there is no single “best” source to use.
You need to evaluate the advertising source for your purpose. Are you looking to tap into search engine traffic? Maybe PPC (such as adwords) is a good idea. Is your need to generate website views without having a budget? Free traffic exchanges may be your best bet.
The fact of that matter is, no ONE source is the “best”. Your situation may be different than someone else’s such as budget, time and need…or combination. So how do you know what will work for you? Testing sources for advertising will help tell you what works the best for YOU. Some people swear by traffic exchanges but since most manual traffic exchanges require lots of time to invest, that might not work for you.
Do your tests, record the results, make changes and try another sources.
Best of luck!