If you have the time, I believe that you should do both. You could outsource the linkbuilding, and then focus on writing your blog...
Backlink from a single blog would not help you much in your serps ranking. If you are anyway good at writing good and relevant content, why not write articles in your niche and submit them to various article submission sites such as ezine! You can include your link within the article or as signature in the end and get backlinks from several sources instantly! Regards, RightMan
I like the permanent aspect of it too. And hopefully one can also get higher page rank over time that can be easily passed over to the main site. For article building. It is something that I have not tried out yet, but I know that I should try out ezine and hubpages. Those are the two that I hear about anyway.
Article Building is a great way building links. am doing article building for quite sometime now and the results are great. why not try it
If you have limited time, then just backlinks from different sites. If yo have time for it, do both. Your blog needs content and backlinks as well, otherwise an empty blog serves no purpose.