The best traffic source is the one that have the best conversion rate for your products @ cheap price or even for free.
you can make any traffic source to be best traffic, it depends on how you apply the methods.
if you're a newbie you would like to start with paid traffic. no much work or experience needed and very targeted.
For me the best resource is Forum signature. And post in relevant threads. 2nd is media buying on relevant sites.. 3rd would be solo ad if you are in making list.