Yeah,if the directory has nofollow attribute, have no sense to submit the website you this kind directory,that is no good to improve your pr or indexed in searche engine!
Both are equally important in its own way. I use directory submission as well as social bookmarking when I need to promote my sites / products. SticKer
They are both useless unless you have quality content. If the content is good enough your site will almost promote itself. So many people on DP waste their time on tinyurl clones or proxy sites, just think of something original...... then promote it via social bookmark sites and directories to begin with!
Definitely both. Bookmarks much better for quick, short term traffic, Directories better for slow, but ongoing traffic.