According to Emarketer.com, this is what some online marketers said in 2005-2006:
It goes in this order:
1. paid search
2. email
3. SEO
4. behavioral targeting
5. contextual targeting
see eMarketer.com - What Works, and What Doesn't, in Online Marketing
It goes in this order:
1. paid search
2. email
3. SEO
4. behavioral targeting
5. contextual targeting
see eMarketer.com - What Works, and What Doesn't, in Online Marketing