Unfortunately, the numbers you seek are very hard for the general public to obtain, because they deal direct with the financial and technical operations of the airlines. What we can come up with is a very rough & crude nm/g ratio. However, as these are coming direct from the manufacturers (who are known to embellish) and do not take into consideration payloads, they are obviously not the whole story. (BTW - I've only bothered to list the airplanes that directly compete)
= 0.170 nm/g
= 0.186 nm/g
= 0.171 nm/g
= 0.150 nm/g
= 0.151 nm/g
= 0.146 nm/g
Like I said before, these numbers are very basic. However, what they appear to show is that the Airbus, as suspected, is more fuel efficient in the current generation. But as the newer generation comes out, we see that they become far less efficient, allowing the Boeing's, who do not lose as much (the -200LR actual goes up a point), to better the A340's efficiency numbers. But again, this does not take into account payloads, which I have yet to see some firm numbers on.
Honor the warriors, not the war.