I'll bet on Boeing.
Major programs like this always have delays, cost overruns, technical glitches, etc. But they always come on line eventually. And after they come on line they need fixes, mods, technology updates, and the rest.
Had Airbus won it would have been no different.
The new world-class tanker is going to happen, and if it's anything like the KC-135 or KC-10, will serve the free world for the next 50 years. Rejoice!