Both are very effective. Why not do both? With your search engines results getting direct traffic and your social media getting referrals, its a win/win situation.
Both techniques are good. Search engine as well as social media marketing helps getting high quality backlinks as well as you can get good amount of traffic. Also, Social Media Marketing is the premier thought leading agency for brands looking to maximize ROI driven social media marketing campaigns.
I think you should do both. Search engine traffic is very important, because this is a way to continue to get new people to your site on a daily basis. Using social networking sites can help the traffic you get keep in connection with you and your site.
Good SEO specialists can help achieve truly amazing results. For example, I use SEO services http://paralabs.us/?curr=usd , so I highly recommend this agency.