KenV,
I would suggest that if the USAF was to change tack, which clearly it won't, Airbus has sold quite a few of these Multi Role Tanker Transport aircraft and so the waiting time would be considerable. I am not aware of the KC46 receiving the same interest?
I suppose the point is if you can still afford in this financial climate to pay a vast amount of cash for an aircraft with a single purpose then great, the KC46 is probably good to go. If you need a true Multi Role platform then I would suggest the MRTT is the choice. I've seen the stands for both, and whilst the MRTT doesn't meet the USAF requirements due to cargo door, the KC46 certainly doesn't meet the RAF requirements for FSTA in terms off Multi Role performance.
It's all quite simple really. Not about which tanker is best,more about which meets the customer requirements.