Shower thought. Monero is technically the most private cryptocurrency, and the best to do it, BUT because of its smaller anonymity-set, it perhaps could be debatable if it indeed it's more private than Bitcoin, no?
Every time you make a Monero transaction, your client picks 15 random inputs from the blockchain as decoys, hiding the true sender, and then it derives a one-time public key that's used to obfuscate the receiver, while simultaneously hiding the amounts transacted every time. And if those weren't enough, all these privacy gains are enforced compulsorily, by the protocol.
It's not debatable.
I'm having a shower thought about it more from the perspective of Law Enforcement in identifying privacy coins users, and because of the smaller anonymity-set, once they identify one group it could make it easier to identify other groups. But if we compare that to Bitcoin - total confusion because the number of users are simply bigger. Would that be a valid argument? ¯\_(ツ)_/¯
What would be more private, let's pretend these are actual numbers of users - 10,000 CoinJoin users or 100 Monero users?