Image Source
There a lots of privacy focused cryptocurrencies but to be honest cash is the most private method to transact. There is no middle man and no public ledger. However, for it to not have a middleman, means it cannot be used online. To use Cash online means being issued a digital representation of that value backed by a middleman who reports your details and provides you permission to use it.
In blockchains, they are far less private because there is a public ledger. Every transaction is there for the entire public to view. With a privacy coin like Monero,Zcash, there is no information to analyze in the public ledger. So this shielded public ledger has allowed you achieve cash like privacy in that there is no middleman, and allowed you to use it online, which cash is unable to do without a middlemen.
