(Late answer) :), imo aside from Borg Cube, almost all those instances where a galaxy class was "supposedly" beaten is because there was almost no shields up on that moment of attack either because enemy ship was cloaked or the weapon configuration was unknown to the federation standard (Jem Hadar : used phased polaron beams)
...but the point here is any ship without shield can easily be destroyed or beaten regardless whether its a galaxy class or a bird of prey, but if you are going to be hypothetical on a scenario where both are shielded and properly configured it all comes down to shield strength and regenerative capabilities and its hull strength, and since a galaxy class or any large ship has both of the qualities it will outlast a cloak capable warship like the BOP and the klingon warbird.
Setting aside Federation Standard Configurations, i'd place my bet on the Modified Voyager thanks to Seven Of Nine / One / Future Janeway for enhancing and augmenting Adaptive Shield and Anti-Borg Armor :) could probably beat any of the enemy ships mentioned