Quote from FlightlessParrot:
"Designed by Lockheed, built by Boeing, marketed by Douglas."
Don't know the answer to the OP's intriguing question, and that may well be it. But if, for example, you compare the B707 with the DC-8, my impression is that the latter was better built (certainly corrosion-wise), but not so successfully marketed overall. Unfortunately for that example, there was no Lockheed equivalent, unless you count the C-141. (Are we extending the discussion into the military?)
Going back to the period between WW2 and 1958, Boeing's only offering that springs to mind is the B-377 Stratocruiser, which was impressive but a commercial (and reliability) disappointment.
Perhaps you are thinking more of the L-1011, B747 and DC-10?