Why is HBAR unique?

I'm intrigued by the concept of HBAR and its potential in the cryptocurrency space. Could you please elaborate on what makes it unique? I understand it's associated with Hedera Hashgraph, but what specific features or advantages does it offer that distinguish it from other cryptocurrencies? Is it the scalability, the consensus mechanism, or perhaps its governance model? I'm keen to know more about its unique selling points and how they contribute to its overall value proposition.