I agree that Darkseid is truly evil. But he also has an honor system and he doesn't want to eradicate all life, he wants to control it. Evil...yes, but his motivations are rule.
As for Apocalypse, while he is tremendously evil and is listed in the honorable mention list, he still is more of a mutant knock off of Thanos. I used popularity and reputation to base this ranking and he couldn't crack into the top 10 because of it.