Actually, all crypto-coins are long-term investment. You won't earn that much if you're going to put your money for a while, a week, a month, or a year. You need to stay with it. There's no fast money. You have to be patient enough to see the results of your hardship. That's just like in planting a tree. You have to wait for some years for it to bear fruits.

Well, ethereum, in my opinion, is a great crypto to invest at for a long term. Among the crpyptocurrencies, ethereum is the 2nd most popular (next only to bitcoin) and the only one which seems to not drop its price so much (it was at 0.073 BTC per ethereum last week, but now, it is at 0.076 BTC per ethereum). So, I can say that it is great for long term investment.