I've come to understand that in various fields like plumbing etc, there are experts assigend and each of them have a ranking #1,2 etc. and each of them have a location Atlanta,Chicago etc.

Now if I want to find the top 10 experts in plumbing in say chicago, how do I go about doing it? Or is this a more of a question for the site administrator?

I sort of understand what you are talking about, but not 100% sure.
AMHD has 1 Plumbing expert and a number of excellent others.

He offers amazing advice that has saved a lot of people time and money.
Now if you are looking for an in-person consult, I doubt this is possible. After all we are on the internet where geography is meaningless.

It depends on your qualifications of an expert. Some 'experts' are simply journeyman plumbers, skilled in practical plumbing but not in the business end. Some experts own a business but can not actually do it. And some own the business and actually do the work. The skill level of each is determined by his personal experience AND desire to do quality work, and ability to do quality work.