Adwords is a different channel and it really depends on what you want. E.g. e-commerce, you'd usually do SEO, Adwords (including product ads), maybe Amazon and Ebay. As long as a channel is profitable, great, one isn't really a substitute for another.
What's nice about Adwords: Instant traffic, independant from organic rankings. Perfect to calculate, even down to the individual product, the business administration guys in a company love it. SEO means cheaper traffic long term, but not as easy to scale and predict short term.