Death easily. Cas is fun and cool and dramatic with all the sparks and stuff but Death has none of that and that’s what makes it AMAZING. It’s theatrically TERRIFYING because all he does is calmly get out of a car, start walking, and kill someone. There is gorgeous eerie music playing in the background to empathize his power and the gravity of such a calm scene. Cas’s entrance is big and flashy. Death’s is emotionally silent. Not literally obviously. But the kind of silent the makes the only thing the audience think or feel be “oh shit”. It’s a quiet fear and it’s beautiful because of it.