It's an interesting question. Is there a better Proof of Work than SHA256?

Assuming these cryptographic mining functions are not REALLY one-way functions, bitcoins PoW is in the future potentially vulnerable to quantum cracking by Shors algorithm, and it is also vulnerable more generally to malicious-majority energy attack (like if mecha-elon musk bought all computers in the world).

Is there a more scarce resource than Work (energy) to use in proving you have done something and sacrificed for it? Maybe "Proof of randomness". True randomness (as opposed to pseudorandomness) is actually as close to perfect information you get. In fact, you can actually extract energy from a string of truly random bits, as was proven in Feynmans work on reversible computing (awesome read). Monte Carlo simulations, particle swarm optimizations, etc, work because even pseudorandomness is so informationally dense.

Or maybe "Proof of Intelligence/Attention/Sentience"? We certainly seem to be alone in the universe, so that seems more scarce than energy. Who knows.