I would say Melbourne.
My family recently flew into there to come visit us in Sebastian-just North of the resort.
We were very impressed with the airport-clean, modern, not crowded, fast.
It took about 1/2 an hour to get to the resort.
They paid a little more to fly there vs. Orlando but it was worth it to be so close.
They took the shuttle on departure day from the resort to the airport and it was fast and not too expensive (the Melbourne Airport Shuttle.)
Hope this helps.
Vero does have an airport but not for commerical flights.