Final answer:
The universal law formulation of Kant's categorical imperative is more compelling because it requires actions to be universally applicable and consistent, thereby creating a reliable moral structure within society.
Step-by-step explanation:
Immanuel Kant posited two formulations of the categorical imperative which serve as universal moral laws — the universal law formulation and the humanity formulation. The universal law formulation instructs that one should "Act only according to that maxim whereby you can, at the same time, will that it should become a universal law", whereas the humanity formulation emphasizes treating humanity, whether in oneself or in others, always as an end and never merely as a means to an end.
The universal law formulation seems more compelling to me because it concerns the moral consistency of our actions and their suitability as a principle for everyone. This approach highlights the need for our actions to be capable of being generalized without leading to contradictions. For instance, if everyone lied, trust would be undermined, rendering the act self-defeating. On the other hand, truth-telling maintains consistency and fosters a society built on trustworthiness.