Plus, it's heavily competition dependant. If you choose a home base with excellent destinations, but with very strong opponents and no slot limits, they are going to crush you painfully. So it's impossible tu say "Cinncinati is a good base", as it depends on the dynamics of the game.
in GW3, when a 732-plane company based in Paris-CDG did collapse, 3 companies did immediatly expand there. It's not random. You'll have more place if you go where opponents are not. That, and what bdnascar3 said : make a good use of your fleet. Choose 1 or 2 categories fit to the lines your airport offers, make the planes fly all day long, be sure to flights spaced enough not to have to much schedule problems, and check your prices on a regular basis(ideal LF is 85%, in general. In some occurences, less. Not often more).