Which blurbs are more valuable

The other day Tess Gerritsen noted a discussion-disagreement about the impact of the internet on book sales. In the course of the general back and forth the subject of blurbs came up--are blog blurbs all that helpful to publishers? This started when two Avon editors politely stated their opinion that, as of right now, newspaper/magazine blurbs are better and NY Times bestseller endorsement are best of all. Many writers and readers wrote in (apparently-I haven't read the source material) to comp