Is there a reason to have "the most" rather than "enough". ATL is the world's busiest airport, so I would think that's the factual answer.

But I would think that you can get almost anywhere you can from ATL from DFW, ORD, etc. with the exception of small towns in the south (trading off small towns in TX, IL, etc.)

If it were me, I'd make a list of the hubs, and then figure out where I want to live. I've been M-F (+/-1) for 20+ years, and if you're anything like me, you'll see the airports, hotels and client sites during the week. Your 'life' will be at your home base. If you hate the South, don't pick ATL over ORD because it has 5.9% more flights.

For actual numbers - Here is the list

I'd say ATL, ORD, DFW, DEN. CLT, IAH plus NYC are the best candidates. PHX, PHL, DTW, MSP, SLC - maybe, if you work in big cities and really like these locations.

I'll add that PIT used to be, and now is certainly not.