Buffalo and Oklahoma City are about 1,119 miles apart by road. Split the difference and you arrive near Indianapolis, the city closest to the halfway point between them. That puts roughly 9 hr 7 min of driving on the Buffalo side and 14 hr 26 min on the Oklahoma City side — the fairest single meeting point among the cities near the middle.
Over this distance most people will fly rather than drive the whole way. Indianapolis still makes a fair, central place for Buffalo and Oklahoma City to converge, splitting the travel instead of asking one side to cross the country.
If Indianapolis doesn't have what you're after, Louisville and Chicago are also close to the midpoint and worth a look — each keeps the drive reasonably balanced between Buffalo and Oklahoma City.
City descriptions adapted from Wikipedia (CC BY-SA); photos via Wikimedia Commons, credited above.