My main interest in cryptocurrency is not in cryptocurrency itself but in the technology it builds on which is Blockchain. Blockchain as a concept is so so interesting and there is a lot of projects that their main goal is to scale this technology to the point it is totally usable in real life.
As for Cryptocurrency itself, I am interested in its decentralized nature and any coin try to go around this nature should not be considered to be on of the cryptocurrency such as Ripple, and then the smart contract but in my opinion, it is not really used as it should have been until this moment.