Bitcoins and ethereum has the most grip in the market, this two coins are highest demand in the market and because of that, i believe that this coin will the only coin who can actually survive for a long term investment.
but nevertheless you should pay attention to coins, which represent some kind of services or some goods. To date, ico companies are very numerous and the multiplication of different crypto-currencies is increasing. But among them there are very promising. Of course they will not be compared to the etherium and Bitcoin, but their prospects for the future are very large.