For me XTRABYTES (XBY) and Spectrecoin (XSPEC) have big potential for huge gains by 2020, both are still in full development and are not just clones of existing coins. XTRABYTES is developping a secure, superfast codeagnostic platform that will solve the know problems of scalability and centralisation thanks to their newly developped Posign consensus algorithm. Spectrecoin is is highly anonymous coin that offers THOR and OBFS4 support as well as stealthstaking, they are the only coin that has successfully bypassed the great firewall of China.
Both dev team are very active and competent and both have a real chance of making a difference in the blockchain market. Both coins are still flying under the radar because they are not spending huge amounts of money on marketing at the moment, they are both focussing on getting their tech right in stead of relying on hollow marketing promisses like a lot other coins out their. If you have the time and patience to let these team do their work you are in for some very nice returns on your investment.