zcash has a chance to win as the most anonymous coin. But it has not yet been released. They have one of the best development teams in the cryptosphere so it is good to wait for this project to be officially online with their mainnet.
I'm very much looking forward to ZCash, but again, like Monero i'd like to know what their plan is for utility beyond just being an anonymous currency. I haven't read into the whitepaper much but I know they use ring signatures for their anonymity too (like XMR and SDC). Cryptography isn't my area of expertise, but to my knowledge, the anonymity methods used by Monero, ShadowCash, and ZCash I believe are all on a similar level of anonymity. If someone could speak to this, and confirm or disprove, that'd be great.