None of them are at the airport, they all involve a shuttle bus ride to wherever they have the vehicles.
There are ten companies with cars actually at the airport: Hertz, Thrifty, Dollar, National, Enterprise, Alamo, Avis, Budget, Payless and Sixt.
Of the companies you listed, I've only dealt with Ace. It was fine but a lot of waiting around. Since that experience I've only ever used the onsite companies.
Routes is a Canadian company that seems to be okay, zezgo I've never heard of.