I have always liked Monero better. It uses complex mixing techniques at spend time to break information into lots of little pieces and spread them around on-chain.
(I am not a cryptographer or a Monero expert so don't take my word for truth. This is my flawed high level understanding of the system.)
When you spend monero your wallet generates a ring signature with random addresses from the blockchain. This strategy is basically to make it exceedingly hard to reassemble that information in a way that can be used to identify the spender. You would have to find the owners of all the addresses in the ring signature and use the process of elimination to identify the true spender. That's really hard to do!
This is a robust privacy system that works in practice. Notice it spreads the trust among many participants. The genius of the system is they are randomly selected from past transactions non-interactively. So they don't need to be online or even be aware that their coins are contributing to someone else's anonymity.
The downside of this system is it's complexity. Monero can't do anything even close to smart contracts.
The trust assumptions are also siloed in a single system. That could be a problem if/when that system is broken. Monero devs are aware of this fact and have been continuously upgrading it's privacy properties for the entire history of the project. It's an arms race. Those devs are elite endurance athletes. Mad respect.
