Arc of a Scythe series by Neal Shusterman
I LOVED this series. The story is so original and each book was filled with twists and turns that I never saw coming. This is one of those series that you can't put down because you want to see what will happen next but at the same time, you never want it to end.
Instead of a dystopian world, this world is "perfect" - death has been conquered, there is virtually no crime, and a cloud computer makes sure everything runs perfectly. But, when there is no death, the world will eventually be overcrowded. So, the world needs Scythes. The Scythes deliver random death in quantities designed to keep the population from growing too large. But, even in a perfect world, too much power in one group of people's hands, means someone will eventually use that power for evil.
Anyway, I'm a little distracted every time I try to write. This is the best I can do right now. Basically, if you ever liked anything Shusterman wrote, read this. If you like dystopian-ish novels, read this. But, it isn't really for the faint of heart - the main characters deal in death, so there is a great deal of it. I wish I could read the story all over again for the first time. :)