It depends really on the content. I would say that providing the post on the blog is on topic, then that would be the best bet long term. BUT do not underestimate directory submissions.

I am sure directory submission is quite good value too, its just that its a bit old compared with blog posts.

I think that blogging is much more natural than maintaining directory in the eyes of SE developers. That is why I think a link in a niche relevant blog post is more valuable concerning ranking.

I quite agree with you on that Bagi, though bad blogs exists but not as many as bad directories which contain nothing but links, links and lot of poor quality links.

As far I understand, directory submission is easy to all and also useful for all webmasters. Blog post is more effective, but this is not easy for all. To post a blog, everyone should sound knowledge on the topic. otherwise the blog posting will be useless. anyways, I also start a blog at Rakib Khan’s Blog Just launch.

I've been writing posts for money in my blogs for while and I had a lot of happy customers.

I think blog posts are more indicated if you need quality back links.

I want to start writing blog posts, but what do I write about?

I have just used directories so far.

From,
Jack @ PODJA Web Solutions

Jack,
You start by writting about things you know very well, you can then branch out to other territories but prepared to research whatever you writeon carefully so that you article will be good quality