for now in 2018 I suggest you can invest and buy as many XRP coins as you can because I see this year there will be a good development from XRP maybe the price can go up again and can be very expensive so you should be able to prepare assets you are XRP.
I bought some XRP last year. and this year they drop 60% less. I bought each for 1$ and now that is 0.4$. so I am at lost at the moment. I don't think it'll increase very soon. so my investment is locked until it recovers. and if I sell it now. I'll be in 100% lose.
In this year, you can say it the year of down market as we are observing the ups and downs below 10k market price and sometimes t gets stable between 6k and 7k dollar price.
So, in such conditions you have to invest here in the Bitcoin and not somewhere else if your savings are enough to get the Bitcoins so as to get it low and to sell it high later. If you desire for short-term then you should not invest here but try out there in the Litecoin which is best for short-term.
If investor wants to go for a long term investment then there is no good choice other than the Bitcoin. On the other side, Ethereum has also a slight character of long term and people are also investing in it so as to get huge profit but still Ethereum is many times lower in price than that of the Bitcoin so ultimately its profit will be low.
Now, for short term the best coin so far considering is the Litecoin which generates profit early for you but that will be low profit even lower than Ethereum, you can see price difference in both.