It depends on the directory or blog. If they are worthless, then so are the links. I would take a link in a blog post over a listing in a directory however. And in some cases, may prefer being in the blogroll over a directory listing.
It's hard to say. I think, that both techniques are worth of time spending on it, but these blogs and directories must be a high quality sites.
I think they are of equal value but the blogs and directories have to be of high quality and they should be dofollow.
Can't possibly answer with knowing if the directory and/or blog are related to your niche... If both are, I'd say blog. Because it's likely to have a more favorable link to text ratio (i.e., lower)...