I'm not sure of your ultimate intent, but I would also add that some of the top producing agents in Marin specialize in certain geographic areas. So even by volume or units, any comparison could be skewed. A top agent in Sausalito might have a third as many units as one in Novato, and the dollar value could easily be the same. Of course, both would possess vastly different market knowledge. That's just Marin.
If you think I can help with a recommendation, just get in touch at any time. Definitely there are some excellent agents in every town here, and likewise some who won't return your calls. I've worked with both and am happy to share my experiences from the lender side.
They might show 100 sales per month, whereas a good single Realtor will sell 3-4 per month.
It just depends upon what you're looking for.
Hopefully this will help to answer your question!
Mary Kay and Kathy