I really do onot know...but I do know that it seeems to rotate.  You see one company for a few years with the most signs and then it changes...see this for years

....and all advertise #1

Tony and Suzanne - The three with the most agents.

I thought you would like that.

Each community seems to have it's favorite.  Here in Santa Clarita, California it's RE/MAX, the Realty Executives then Keller Williams.

CB, KW, and c21 are the largest franchises in my market.  But we have independents at the top as well. 

Recognized are ReMax and KW. However, franchise that closes the most are from agents that never seems to be able to sit still.

I BELIEVE the top 3 in residential in our area are all indies!

First Weber has the lions share in our area.

I'm surprised to see RE/MAX mentioned so often. I think it depends on who you ask. I notice a lot of  Williams Trew, Alexandra Chandler in the culture district as well as Wilco Realtors.  Country area C-21, KW 

Berkshire Hathaway
Pacific Sothebys
Coldwell Banker
(Rancho Santa Fe only) Barry Estates

I do not care nor even think about franchise names or brands.  All of them have some great agents as well as some really terrible ones.

RE/MAX is a leader in our market area.

Long and Foster and Berkshire Hathaway are neck and neck.  After that it is a close race between William E Wood and Coldwell Banker.