well.... the Intruder was proven in serious combat over 30 years - can't have been all that bad
but to some extent they were tasked with different missions - the A-6 was designed to fight & support another Korean War (and did in Vietnam) - the Buc was an anti-ship strike aircraft designed from the outset to drop small A weapons - the fact that they were later re-roled to land attack was really due to financial constraints