Which of them is good ?

All those things are good for your site. But some forums and social media sites are now nofollow. It won't help you get good result.

 

All of them are good for SERP's but social bookmarking is best.

 

Don't limit yourself to just 1 method of link building. You need a diversity of links so make sure you're getting a good number of links from a variety of sources using a variety of methods.

I've heard we're up to nearly 400 factors.

 

We cannot compare any of these. As a man is mothing without legs, arms, eyes same like that everything has different actions. So these three factors helps to promote the site.

 

Both content and Links are important. You should have a very good contents with relevant keywords, plus do link building in all possible way like directories, blog and forums submissions.

 

Exactly there are lots of factors involved in the rankings so it is not good idea to focus only one of them.

 

From my point of view.....Forum posting is the best among this three.
In directory Submission you can't promote your Keyword with website.

 

Hello friend,

social bookmarking is good for SERP but you have to do all off page activities for higher ranking.

 

I prefer social book marking first which can bring you quality back link and Forums next which can bring you back link and knowledge. Finally directory submission which bring you late results.

 

All activities are good like forums posting,blog commenting and article submisison.

 

Hi,
Your both factors are good for the seo.You have follow these factors effectively and and have to make patience for a good page rank.Besides these, there are many steps to be
followed like social bookmarking which plays important role in seo.

 

Above mention all the 3 methode are Good, better to use all of them you will get Good result, If you need very quick result Social Bookmarking can give it to you!

 

To get best result you should have to use complete SEO techniques ....this is very important

 

SEO is like an all out war. You need to use everything at your disposal: On-site SEO, Directory submit, Guest Posts, Social bookmarking, Social Media (fan pages), Blogs. It all helps.

 

well all 3 of them are good and there are many more.

 

Directory submission is good for the SERPs but with directories, the problem is they want a link back to your homepage, if you gave all of them that want a link back what they want, your site might be devalued by the search engines

 

Yes, Mr. dougadam
I know it very well, but i want the best out of three, I am performing all the regular activities as well but I want the best one to be targeted more carefully.

 

All are good. But in my experience the blog commenting is the best activity to increase serps. You haven't include this activity here.

 

you've not included the most important activity i.e. having quality content in your website

 

Here’s another social bookmarking site : http://www.humansthink.com . It’s dofollow.