Didier Bizimungu had a post on his SEO News Blog that circulated around the industry. The subject was the top 10 SEO leaders, and since Didier asked for my opinion, I thought I'd share it publicly. Here's Didier's list:

1. Daron Babin
2. Matt Cutts
3. Rand Fishkin
4. Jim Boykin
5. Aaron Wall
6. Danny Sullivan
7. Barry Schwartz
8. Bill Slawski
9. Todd Malicoat
10. Andy Beal

These are certainly influential and important folks (except for number 3 - that guy's small time), but by no means do I feel this list is accurate in any sense. I think that in order to come up with a list of influencers, it's first critical to think about the criteria you'd judge. These are mine:

• Ability to Reach a Large Audience
  Whether through blogs, feeds, a forum, traditional media, or podcasts, an influencer needs to have a sizable reach.
• Ability to Influence Decision Makers
  A person with the ability to speak directly to people at the search engines, from the advertising side to the search engineers to the executives, as well as important folks in media, advertising, and related businesses (think Amazon, IAC or IBM).
• Credibility
  There are plenty of folks with large audiences who have a credibility gap - if you don't have the belief and trust of your listeners, you may be entertaining or even valuable, but your influence wanes. Credibility in our industry is about more than just telling the truth - it also includes a component of importance; thus, while you might consider SEOmoz "credible" in the usual sense of the word, for these purposes, I'd give a low credibility score. Unless some other folks write about the same subject and spread our ideas, we're fairly insulated. 

Based on these criteria, here's who I'd rank in the top ten in the search marketing industry and my relative score levels (out of 10; higher is better) for each. Note that I've opted only to include those folks who regularly participate in industry gatherings (SES, Pubcon, etc.), thus excluding obvious list-toppers like Eric Schmidt or Jerry Yang:

1. Danny Sullivan
   Audience Size: 8/10 (used to be even higher at SEW, and probably will again soon - this also includes the entire SES conference audience and surrounding media)
   Decision Makers: 10/10
   Credibility: 10/10
2. Michael Arrington
   Audience Size: 10/10
   Decision Makers: 9/10
   Credibility: 7/10 (while Techcrunch matters, it doesn't have the same level of impact that Danny does with the search industry specifically)
3. Matt Cutts
   Audience Size: 7/10
   Decision Makers: 9/10
   Credibility: 8/10
4. John Battelle
   Audience Size: 7/10
   Decision Makers: 8/10
   Credibility: 8/10
5. Brett Tabke
   Audience Size: 8/10
   Decision Makers: 7/10
   Credibility: 8/10 (the only reason I'd put him behind John is because he contributes so infrequently to the search world's dialogue)
6. Tim Mayer
   Audience Size: 4/10
   Decision Makers: 8/10
   Credibility: 7/10
7. Barry Schwartz
   Audience Size: 7/10
   Decision Makers: 7/10
   Credibility: 7/10
8. Shawn Hogan
   Audience Size: 8/10 (all of Digitalpoint is included here)
   Decision Makers: 4/10
   Credibility: 5/10
9. Philipp Lenssen
   Audience Size: 6/10
   Decision Makers: 6/10
   Credibility: 6/10
10. Jeremy Schoemaker
    Audience Size: 7/10
    Decision Makers: 6/10
    Credibility: 5/10
    (I struggled putting Shoemoney here, as there may well be some quieter, behind-the-scenes folks who have extraordinary influence in the search world. I also suspect that someone like Greg Boser, Mike Grehan, or Andrew Goodman might belong here, despite their smaller audiences, simply because of their ability to connect with decision makers)

While my list has preserved a few of Didier's choices, it's largely unique. While owners of SEO/M firms like myself, Jim Boykin, and Aaron Wall may have significant audiences, it's my general belief that the folks above all have a greater power to influence. My scores would probably look something like:

• Rand Fishkin
  Audience Size: 6/10
  Decision Makers: 6/10
  Credibility: 5/10

Now, Didier's criteria could easily have been based on other crtieria like exposure or name recognition, in which case I'd still dispute a few of his choices. He noted in his post that it was predicated on "influence and the amount of time they’ve sacrificed in the industry." By that criteria, I think my list holds up fairly well, though folks like Arrington and Battelle are slight outsiders to the specific field of search marketing.

Your opinions?