The both seo activities have their own importance such as SBM gives backlink and traffic too but by doing post on social sites gives only traffic to your site.
It's better to do both of them if you want to see awesome results. Try to outsource some of your work if you don't have time and don't forget the rest of the SEO techniques.
Hi Bookmarking and social network sharing both brings traffic, visitors, bookmarking is good we will get backlinks and improvements in keyword
both the activities works really well.Bookmarking and social networking both are different form of seo. The bookmarking are performed for getting back links but the social networking sites are used in spreading information across the world as soon as possible.
You can do on social networking websites if there is time consumption problem. Otherwise do both, both are important according seo point and social media.
Stumbleupon,reddit,diigo,delicious and sites like that. Do some research on the google about social bookmarking sites. By the way, i do both, social networking and bookmarking.