That's an informative link you posted, Perth.
Some general observations can be readily made as to what constitutes a highly-ranked airport by pax movements .....
1- has to be a hub
2- has to be a strong O&D market in its own right (ie large business center)
3- has to be relatively free of competing airports in their geographic area
4- has to have a robust infrastucture and growth potential
Now, let's look at the busiest airports in light of above....
ATL -- 1- very strong, 2- so-so, 3- very strong, 4-very strong
ORD -- 1- very strong, 2- very strong, 3- competes with MDW, 4- very strong
LAX -- 1- very strong, 2- very strong, 3- competes with ONT, SNA, BUR, 4-very strong
LHR -- 1- very strong, 2- very strong, 3- competes with LGW, STN, LTN, LCY, 4- limited growth potential
"In God we trust, everyone else bring data"