What is the most efficient marketing technique? For national level businesses? For local businesses? I would say it is article marketing for national level businesses but I may be wrong.
Advertising with GOOD ads. That's it. Sorry, but article marketing is bottom of the barrel. That is, if you are talking about getting good traffic.
ppc marketing is the best and it dosen't have to come from google adwords, but they are a good source.
Customer satisfaction - Word of mouth. You never know, a good review post from a customer in his personal blog can massively increase your sales.
good original viral article is hard to come by, and it could be expensive.. PPC is predictable, and works, but for the short term. I agree, most of the articles are bottom of the barrel, not worth the bandwidth it takes to download. So after all the pros and cons, you need to look at the industry and business you are trying to promote. If you have a boss to answer to, PPC is the way to go... result is easily measurable
All marketing methods can work. You really just need to be GOOD at whatever method you are using. Article marketing is probably the easiest for new marketers.
Target the population who is going to click or buy the product i am selling and advertise in the best way possible to them.