As two of the DC Universe's most powerful forces imaginable, the destruction caused by both Darkseid and the Anti-Monitor is hard to comprehend. But even on a scale most can't even conceive, the question must be asked: Who among the two has killed more?
Admittedly, it's a hard thing to try and calculate, since each figure is synonymous with universal calamity and death. Throughout the DCU, the very name of Darkseid sends a chill down the spine of those who have lived to see his Parademon armies tear down civilizations in the name of conquest. As for the Anti-Monitor, no one can forget the countless worlds that perished during his large-scale attack during Crisis on Infinite Earths. The two antagonists have challenged the combined might of DC's best heroes and both have survived, making each foe a force to be reckoned with.
Of course, between the two of them, one has to have killed more. On DC's own blog, they responded to a query about the number of victims of each Crisis, which they define as the "seven major events with reality-altering implications." As the main threats of Crisis on Infinite Earths and Final Crisis, this is the closest there likely is to an official body count for either Darkseid or the Anti-Monitor. When it comes to numbers, the Anti-Monitor clearly comes out on top, being described as taking "Countless infinities of lives" because of reality whittling down to one universe. For Final Crisis, the blog lists the death toll as "unclear, but likely much less than Infinite Crisis." However, the post contends that Darkseid's numbers are lower because he was seeking control rather than death.
Granted, this blog entry is centered around Crisis events and doesn't take into account other events that may bolster Darkseid's numbers. After all, he's a conqueror who has crushed a number of civilizations under his heel. Not only that, his forces extend all across the multiverse, giving him just as far a range as the Anti-Monitor. He may desire universal subjugation to his will, but there's no doubt that he's got a body count that exceeds DC villains like Joker or Lex Luthor.
Unfortunately, there's just absolutely no way he can compete with the Anti-Monitor's level of devastation. The villain permanently killed off entire universes with an untold number of sentient beings residing in them. There's a chance destroying just one world would have helped the Anti-Monitor eclipse Darkseid, but dispatching with "countless infinities" puts him on a level that defies comprehension. The truth is Darkseid represents subjugation rather than destruction and, as such, his body count isn't going to reflect abject slaughter like the Anti-Monitor's. When it comes to annihilation in the DC Universe, Darkseid just can't compete with the Anti-Monitor.
Source: DC