The three altcoins I have are ETH, LTC and the last but not the least is DOGE. ETH has features of smart contract functionality which I like most. LTC adopted SegWit, the Lightning Network and is nearly identical to Bitcoin. It also has some technical improvements over Bitcoin. When it comes to DOGE there is nothing special with the coin but it is one of those undervalued coins and according to the DOGE community it is scheduled to reach the Moon's surface in 2019 so watch out! Actually, every investors has its own basis and perception on the altcoin when investing and we have different kind of methods and strategies so its up to you how you deal with it.