With the recent changes in the google algorithm it is important that you mix your links. Don't just aim for profile, and comment links. You should also try to get backlinks from article sites, directories. Articles sites are ranked well because they have more content and google prefers content.
Social bookmarking sites don't do well now a days still a few of them are alive and will get themselves indexed fast. So if you put content on them, they will get indexed and traffic will come from Social Bookmarking sites.
