Hush is a cryptocurrency and messaging protocol that is focused on privacy. It uses a the equihash mining algorithm, which is a Proof-of-Work (PoW) consensus mechanism. It offers a high degree of privacy, and allows users to transact and send messages anonymously.
Hush is a fork of Zcash, and uses zk-SNARKS for zero-knowledge cryptography. Hush will allow developers to deploy Ethereum smart contracts on the Hush network.
The founders of Hush are closely associated with Komodo.

Grin Coin is a community driven blockchain project that aims to create a lightweight mimblewimble blockchain that will enable anonymous transactions. Grin has a Proof-of-Work consensus mechanism. Transactions are executed while hiding addresses and amounts.

Bitcoin Private is a community-driven fork of the Bitcoin protocol. It is somewhat unique in that it was created as a result of a privacy-focused co-fork of Bitcoin and ZClassic. Coins were distributed on a 1:1 basis to BTC and ZCL holders. Bitcoin Private (BTCP) uses the same privacy technology as ZClassic (zk-snarks). Transactions are published on a public blockchain, but the sender, recipient and other transactional metadata remain anonymous. Bitcoin Private has a larger block size, and enables anonymous transactions that are more secure than the original Bitcoin protocol.