Rapping, I think. Screaming, while hard on the vocal chords, isn't as complex as smoothly and quickly knocking out a series of rhymes. It requires less thinking and more physical experience.
But it's somewhat like saying, which is harder, bench pressing 600lbs or performing surgery? They both require different skills and both can be achieved eventually if one works at it.
English
-
That is a very good answer, thank you. I agree that both require different skills.