I have flown in a B767 since my first summer, no joke. AA uses them to do Boston-Paris.
It is quite possibly the worst plane I've ever been in. As much as I love the 777, I think the 767 is uncomfortable and badly designed- comfort wise, not safety wise. Likewise, I hate the 757, again passenger wise it is just horrible. I feel constricted and as I I were in a streched out 737- I hate the 3-3 seating.
i have to say my vote goes to Airbus because the A330 is comfy and I feel alot more comfortable in the A320s. (I have never been in an A340, so can't comment)