QTUM is a smart contract platform that was forked from Bitcoin core to feature Ethereum-style smart contracts and proof-of-stake consensus. QTUM has stiff competition from Ethereum for developers who want to build on the QTUM platform, and developers have largely chosen to build on Ethereum thus far. I'm dubious about QTUM until it sees a rise in projects, active developers, active addresses, and transaction volume, as well as proof that the platform has benefits over Ethereum and real-world use cases.
One of the Qtum currency's biggest advantages is its usage of mobile technologies which is great.