While both KCN (potassium cyanide) and HCN (hydrogen cyanide) are highly toxic, KCN is often considered 'better' in specific contexts due to its physical properties and ease of handling in certain applications. KCN is a solid, making it easier to measure and control, while HCN is a gas at room temperature, posing a greater risk of inhalation. However, both are extremely dangerous and require strict safety protocols when used. The 'better' designation depends heavily on the specific application and the available safety measures.