>But for normal usage-as-a-currency, I am a huge believer in XMR (monero), which masks who you're sending money to
There was a talk[1] a few years ago that basically argued that this property only really holds if you look at individual transactions in isolation. It basically boils down to: if you make one transaction to a darknet market, it's impossible to know whether you were actually sending to a darknet market, or whether that was just a decoy transaction. However, if you make repeated transactions to a darknet market, the chances that all of your transactions had a darknet market decoy approaches zero, and you'll be considered suspicious. At that point the police can get a warrant to search your house, or put surveillance on you so they can catch you slipping up irl.
That is a weakness of decoy based systems. This chart [1] shows how various blockchain designs offer different tradeoffs in privacy leaks versus scalability.
There was a talk[1] a few years ago that basically argued that this property only really holds if you look at individual transactions in isolation. It basically boils down to: if you make one transaction to a darknet market, it's impossible to know whether you were actually sending to a darknet market, or whether that was just a decoy transaction. However, if you make repeated transactions to a darknet market, the chances that all of your transactions had a darknet market decoy approaches zero, and you'll be considered suspicious. At that point the police can get a warrant to search your house, or put surveillance on you so they can catch you slipping up irl.
[1] https://www.youtube.com/watch?v=9s3EbSKDA3o core argument starts at around 10 minutes.