Ethereum should be a good choice to invest because they are quite active and also promoting it very nicely. Recently even darknet as accepted it as a payment network on their site. As long as if more and more people start using a coin. Its demand and popularity will go up and prices also slowly move up. Soon bitcoin transaction fees will not be good for the smaller transaction so sure another altcoin will pick up for the smaller transaction, and Eth has an excellent opportunity.
Ethereum is a great investment indeed. But I think now the price is too high, it is risky to invest in it. Perhaps it will rise and cost a lot more than $100 but who knows when this will happen. The same holds for litecoin. The price is quite down now. I am waiting for it to become around $20 or a bit less and then I'll definitely buy some.
Other coins might be good as a temporary investment but then you have to be very careful and react fast on price changes.
Altcoins are still growing in price. I think now is not the time to invest but to wait and see what happens.