What is the most Decentralised blockchain?

Could you please elaborate on what makes a blockchain the most decentralised? Are there specific metrics or criteria that can be used to determine the level of decentralisation in a blockchain network? Is there a particular blockchain platform that is widely considered to be the most decentralised, and if so, what are its distinguishing features that set it apart in this regard? Additionally, how does the decentralisation of a blockchain impact its security, scalability, and overall performance?