i see the future. ether will be 1k$ in 2018. 
Nowdays a lot of dumpers.
Ethereum is good. Because Eth is the best (number 1) altcoin and proven good and the price&value is stable.
But, Better you split your investments. Like Ethereum + Bitcoin. This 2 coins is a monster and can make you much profit.
Here some good altcoins for long-term :
Waves, LTC, XRP, Bitcoin Cash, Ethereum, Bitcoin.