Determining which type of blog attribution to use depends on: 1) the context; and 2) medium that you're using.

Context can range from informal to formal, silly to serious. Additionally, determining the correct method of attribution depends what you want to credit: an idea, a comment to an entry, or an exact passage.

The medium factor is farily open ended. Print publication, online publication, judicial brief, academic paper, business research, and blog are just some of the available media where attributing a blog may be necessary.

A few examples:
a) an required academic research paper for a law school course would probably use a formalized citation attribution to a quoted blog;
b) a blog posting about another blog discussion would probably use an informal link and/or mention of the blog's title;
c) a legal brief submitted to the court would definitely use formal citation.