As many people have already pointed out, Petofi was at least honest (other than passing himself under a phony name) about his motives and what he wanted for the most part. Yes he was evil, but considering the amount of power he had and/or wanted you kind of expect it from him.
Trask, on the other hand, was supposed to be a servant of God when he proved time and time again he wasn't. Maybe he THOUGHT he was, deluded, twisted wretch that he was. But he was guilty of child abuse, murder, attempted murder, gaslighting....the guy was a sadistic, greedy monster. A human one at that too.
So, yes, out of the two I would agree that Trask was more evil. Not saying it makes Petofi any less evil, just maybe a inch or two when compared to the likes of Gregory.