PBS Idea Channel - Are the Titans from Attack on Titan Evil? | Idea Channel | PBS Digital Studios

But if the Daleks believe they are doing good, are they truly evil?

It was noted, Titans have no digestive system and will eventually vomit up all their victims. (ew, nasty)
They eat, simply "for pleasure" as one of the characters noted.

Based on that, I would say if they are aware, they're taking a life that will never be restored, that does put them within the category of Evil or cruel.