In my opinion, sugar's df is the most frightening one because it literally erases someone's existence in instant. And what makes it more frightening is how simple it works, just touch the enemy with his/her palm, the enemy will turn into a toy and instantly the memory of him/her in the entire OP world before he/she become a toy will be erased completely as if he/she never existed before. And also it seems once you become a toy, you will lose all your power and just becime a mere powerless toy. Thho i dont know if haki can protect you from turning into a toy.
How about yours nakama?
How about yours nakama?