Actually my stance is that the Imperium is as bad as everyone else. There is no light in the darkness, there isn't even any real grey. There is no hope, salvation was burned and buried long ago. All that remains is to see how long it takes for the crumbling shell of humanity to die.
The Imperium kills and enslaves children, makes no distinction between innocent and guilty, drives enslaved and indoctrinated masses into hails of cannonfire, tears apart it's own people to turn them into weapons, destroys the very souls of it's own people to make cyborg forklifts, liquifiy those who die in battle to feed to their fellow soldiers as nutrient paste, crush the populace with factory labour the likes of which would make a Victorian workhouse seem like a holiday, poison the masses with chemical waste, value human life less than they do the flak armour it can wear into battle, provide entire worlds for the pleasure of former notaries of government while people choke on smoke and sleep on rags and countless other wrongs besides.
All in the name of preserving something it lost long ago. Worse than lost even, it took so many of the little things, the quiet moments, the compassion, the mercy, the hope of it's people and it killed them for being inefficient. It is a society where slowing down factory work because of crippling illness receives a beating, where attempts to understand why things are the way they are invites death and kindness is viewed with contempt at best.
It drew the attention of the gods after the Fall deliberately, it gave birth to the sons who would give Chaos an army, indeed it even gave birth to that army. The Eldar birthed monsters, but it was mankind who worshipped them, who called out to them and who call to them still. It is mankind who wage war in the hopes of defeating gods who personify that same war.
In any other reality to struggle and strive would be the greatest way to defeat the gods, in 40k it is the main source of their power. The galaxy turns according to designs millenia in the making and is embroiled forever in the machinations of being who were born from the minds of all mortals but shaped by man above all others.
The Imperium is the only form 'humanity' can survive in outside of Chaos, but much like the Interex, the Terran warlords, the people of Nostromo and countless others before them, what is surviving isn't truly worthy of the name human anymore.