Etherium is the best coin to invest now there is lots of successful ICO already implemented on ethereum blockchain that's running well . Lots of ICO's are coming based on ethereum blockchain. Ethereum ranks second next to bitcoin, and it is used by many holders of altcoin, as exchanges of new token in the different sites, and in the market place, if you will invest in ET, you do not need much money for investment, because ETH is lower in price value than BTC
Even if you are not planning to invest in any ICO, still, you have to invest in Ethereum. Its popularity is great, and it will be growing only. Thus, the price of this altcoin will be also going up.
For me ethereum are very promising coin and you can rely on it with your long term investment. You can buy more coins and keep it for long term, you can try to keep it for about six months and see what is the value after.