I'm not a fan of the term "top". Sometimes I find "top" agents don't have the time of day, not even for a fellow agent.
Are you asking your colleagues as in you're searching for a new brokerage? :)
Or are you inquiring as to what a buyer or seller should look for in a real estate company, in general?
KK German, Wainwright Real Estate
(FYI, I am a fan of WEW. I find their agents to be well trained and down to earth. No airs for the most part.)