Answer:
Undo.
Step-by-step explanation:
While copy and paste seems nice in some situations, I think undo would be more useful. I could solve any of my mess ups, and even better, if I were to be perfectionist, I could undo my choices and try different choices and paths until achieving my perfect situation. And who knows, if I ever were to regret my decision, I could undo my choice of undo and choose copy and paste instead.