Bitcoiin is a cryptocurrency that was created to address some of the issues that have plagued the original Bitcoin ecosystem. It's Proof-of-Work (PoW) consensus mechanism is designed to decrease transactions times and fees, as well as make mining rewards easier to earn.

QChi is an Ethereum-based token with no clear benefits. Their marketing materials do not provide any specific information about their roadmap or what advantages it offers compared to other cryptocurrencies.

Ravencoin is a blockchain created by the owner of Overstock.com. It is a use case specific blockchain for the declaration of ownership of digital assets. Ravecoin is a fork of Bitcoin, and was originally funded by Medici Ventures, a blockchain investment fund owned by Overstock.com.
Ravencoin's name is inspired by the use of Ravens in sending messages, and its blockchain is designed to carry statements of truth about who owns what asset. The developers created a new consensus algorithm called x16r to solve the problems of centralized ASIC mining. The algorithm is unique in that it consists of 16 different hashing algorithms whose order are randomly changed.